{
  "language": "Solidity",
  "sources": {
    "contracts/token/ERC721/sovereign/SovereignNFT.sol": {
      "content": "// contracts/token/ERC721/sovereign/SovereignNFT.sol\n// SPDX-License-Identifier: MIT\npragma solidity 0.7.3;\npragma experimental ABIEncoderV2;\n\nimport \"@openzeppelin/contracts-upgradeable-0.7.2/token/ERC721/ERC721Upgradeable.sol\";\nimport \"@openzeppelin/contracts-upgradeable-0.7.2/token/ERC721/ERC721BurnableUpgradeable.sol\";\nimport \"@openzeppelin/contracts-upgradeable-0.7.2/introspection/ERC165Upgradeable.sol\";\nimport \"@openzeppelin/contracts-upgradeable-0.7.2/access/OwnableUpgradeable.sol\";\nimport \"@openzeppelin/contracts-upgradeable-0.7.2/utils/CountersUpgradeable.sol\";\nimport \"../IERC721Creator.sol\";\nimport \"../../../royalty/ERC2981Upgradeable.sol\";\n\ncontract SovereignNFT is\n    OwnableUpgradeable,\n    ERC165Upgradeable,\n    ERC721Upgradeable,\n    IERC721Creator,\n    ERC721BurnableUpgradeable,\n    ERC2981Upgradeable\n{\n    using SafeMathUpgradeable for uint256;\n    using StringsUpgradeable for uint256;\n    using CountersUpgradeable for CountersUpgradeable.Counter;\n\n    struct MintBatch {\n        uint256 startTokenId;\n        uint256 endTokenId;\n        string baseURI;\n    }\n\n    bool public disabled;\n\n    // Mapping from token ID to the creator's address\n    mapping(uint256 => address) private tokenCreators;\n\n    // Mapping from tokenId to if it was burned or not (for batch minting)\n    mapping(uint256 => bool) private tokensBurned;\n\n    // Mapping from token ID to approved address\n    mapping(uint256 => address) private _tokenApprovals;\n\n    // Counter to keep track of the current token id.\n    CountersUpgradeable.Counter private tokenIdCounter;\n\n    MintBatch[] private mintBatches;\n\n    // Default royalty percentage\n    uint256 public defaultRoyaltyPercentage;\n\n    event ContractDisabled(address indexed user);\n\n    event ConsecutiveTransfer(\n        uint256 indexed fromTokenId,\n        uint256 toTokenId,\n        address indexed fromAddress,\n        address indexed toAddress\n    );\n\n    function init(\n        string calldata _name,\n        string calldata _symbol,\n        address _creator\n    ) public initializer {\n        require(_creator != address(0));\n        defaultRoyaltyPercentage = 10;\n        disabled = false;\n\n        __Ownable_init();\n        __ERC721_init(_name, _symbol);\n        __ERC165_init();\n        __ERC2981__init();\n\n        _setDefaultRoyaltyReceiver(_creator);\n\n        _registerInterface(calcIERC721CreatorInterfaceId());\n\n        super.transferOwnership(_creator);\n    }\n\n    modifier onlyTokenOwner(uint256 _tokenId) {\n        require(ownerOf(_tokenId) == msg.sender, \"Must be owner of token.\");\n        _;\n    }\n\n    modifier ifNotDisabled() {\n        require(!disabled, \"Contract must not be disabled.\");\n        _;\n    }\n\n    function batchMint(string calldata _baseURI, uint256 _numberOfTokens)\n        public\n        onlyOwner\n        ifNotDisabled\n    {\n        uint256 startTokenId = tokenIdCounter.current() + 1;\n        uint256 endTokenId = startTokenId + _numberOfTokens - 1;\n\n        tokenIdCounter = CountersUpgradeable.Counter(endTokenId);\n\n        mintBatches.push(MintBatch(startTokenId, endTokenId, _baseURI));\n\n        emit ConsecutiveTransfer(startTokenId, endTokenId, address(0), owner());\n    }\n\n    function addNewToken(string memory _uri) public onlyOwner ifNotDisabled {\n        _createToken(\n            _uri,\n            msg.sender,\n            msg.sender,\n            defaultRoyaltyPercentage,\n            msg.sender\n        );\n    }\n\n    function mintTo(\n        string calldata _uri,\n        address _receiver,\n        address _royaltyReceiver\n    ) external onlyOwner ifNotDisabled {\n        _createToken(\n            _uri,\n            msg.sender,\n            _receiver,\n            defaultRoyaltyPercentage,\n            _royaltyReceiver\n        );\n    }\n\n    function renounceOwnership() public view override onlyOwner {\n        revert(\"unsupported\");\n    }\n\n    function transferOwnership(address) public view override onlyOwner {\n        revert(\"unsupported\");\n    }\n\n    function deleteToken(uint256 _tokenId) public onlyTokenOwner(_tokenId) {\n        burn(_tokenId);\n    }\n\n    function burn(uint256 _tokenId) public virtual override {\n        (bool wasBatchMinted, , ) = _batchMintInfo(_tokenId);\n\n        tokensBurned[_tokenId] = true;\n\n        if (wasBatchMinted && !ERC721Upgradeable._exists(_tokenId)) {\n            return;\n        }\n\n        ERC721BurnableUpgradeable.burn(_tokenId);\n    }\n\n    function tokenCreator(uint256)\n        public\n        view\n        override\n        returns (address payable)\n    {\n        return payable(owner());\n    }\n\n    function disableContract() public onlyOwner {\n        disabled = true;\n        emit ContractDisabled(msg.sender);\n    }\n\n    function setDefaultRoyaltyReceiver(address _receiver) external onlyOwner {\n        _setDefaultRoyaltyReceiver(_receiver);\n    }\n\n    function setRoyaltyReceiverForToken(address _receiver, uint256 _tokenId)\n        external\n        onlyOwner\n    {\n        royaltyReceivers[_tokenId] = _receiver;\n    }\n\n    function _setTokenCreator(uint256 _tokenId, address _creator) internal {\n        tokenCreators[_tokenId] = _creator;\n    }\n\n    function _createToken(\n        string memory _uri,\n        address _creator,\n        address _to,\n        uint256 _royaltyPercentage,\n        address _royaltyReceiver\n    ) internal returns (uint256) {\n        tokenIdCounter.increment();\n        uint256 tokenId = tokenIdCounter.current();\n        _safeMint(_to, tokenId);\n        _setTokenURI(tokenId, _uri);\n        _setTokenCreator(tokenId, _creator);\n        _setRoyaltyPercentage(tokenId, _royaltyPercentage);\n        _setRoyaltyReceiver(tokenId, _royaltyReceiver);\n        return tokenId;\n    }\n\n    ///////////////////////////////////////////////\n    // Overriding Methods to support batch mints\n    ///////////////////////////////////////////////\n    function tokenURI(uint256 _tokenId)\n        public\n        view\n        virtual\n        override\n        returns (string memory)\n    {\n        (bool wasBatchMinted, , string memory baseTokenUri) = _batchMintInfo(\n            _tokenId\n        );\n\n        if (!wasBatchMinted) {\n            return super.tokenURI(_tokenId);\n        } else {\n            return\n                string(\n                    abi.encodePacked(\n                        baseTokenUri,\n                        \"/\",\n                        _tokenId.toString(),\n                        \".json\"\n                    )\n                );\n        }\n    }\n\n    function ownerOf(uint256 _tokenId)\n        public\n        view\n        virtual\n        override\n        returns (address)\n    {\n        (bool wasBatchMinted, , ) = _batchMintInfo(_tokenId);\n\n        if (!wasBatchMinted) {\n            return ERC721Upgradeable.ownerOf(_tokenId);\n        } else if (tokensBurned[_tokenId]) {\n            return ERC721Upgradeable.ownerOf(_tokenId);\n        } else {\n            if (!ERC721Upgradeable._exists(_tokenId)) {\n                return owner();\n            } else {\n                return ERC721Upgradeable.ownerOf(_tokenId);\n            }\n        }\n    }\n\n    function approve(address to, uint256 tokenId) public virtual override {\n        address owner = ownerOf(tokenId);\n        require(to != owner, \"ERC721: approval to current owner\");\n\n        require(\n            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),\n            \"ERC721: approve caller is not owner nor approved for all\"\n        );\n\n        _approve(to, tokenId);\n    }\n\n    function _isApprovedOrOwner(address _spender, uint256 _tokenId)\n        internal\n        view\n        virtual\n        override\n        returns (bool)\n    {\n        address owner = ownerOf(_tokenId);\n        return (_spender == owner ||\n            getApproved(_tokenId) == _spender ||\n            isApprovedForAll(owner, _spender));\n    }\n\n    /**\n     * @dev Approve `to` to operate on `tokenId`\n     *\n     * Emits an {Approval} event.\n     */\n    function _approve(address to, uint256 tokenId) internal override {\n        _tokenApprovals[tokenId] = to;\n        emit Approval(ERC721Upgradeable.ownerOf(tokenId), to, tokenId); // internal owner\n    }\n\n    /**\n     * @dev See {IERC721-getApproved}.\n     */\n    function getApproved(uint256 _tokenId)\n        public\n        view\n        virtual\n        override\n        returns (address)\n    {\n        address receiver = royaltyReceivers[_tokenId];\n        (bool wasBatchMinted, , ) = _batchMintInfo(_tokenId);\n        bool exists = (wasBatchMinted || receiver != address(0)) &&\n            !tokensBurned[_tokenId];\n\n        require(exists, \"ERC721: approved query for nonexistent token\");\n\n        return _tokenApprovals[_tokenId];\n    }\n\n    function _transfer(\n        address _from,\n        address _to,\n        uint256 _tokenId\n    ) internal virtual override {\n        require(_tokenId != 0);\n\n        (bool wasBatchMinted, , ) = _batchMintInfo(_tokenId);\n\n        if (\n            wasBatchMinted &&\n            !ERC721Upgradeable._exists(_tokenId) &&\n            !tokensBurned[_tokenId]\n        ) {\n            _mint(_from, _tokenId);\n        }\n\n        ERC721Upgradeable._transfer(_from, _to, _tokenId);\n    }\n\n    function totalSupply() public view virtual override returns (uint256) {\n        return tokenIdCounter.current();\n    }\n\n    function _batchMintInfo(uint256 _tokenId)\n        internal\n        view\n        returns (\n            bool _wasBatchMinted,\n            uint256 _batchIndex,\n            string memory _baseTokenUri\n        )\n    {\n        for (uint256 i = 0; i < mintBatches.length; i++) {\n            if (\n                _tokenId >= mintBatches[i].startTokenId &&\n                _tokenId <= mintBatches[i].endTokenId\n            ) {\n                return (true, i, mintBatches[i].baseURI);\n            }\n        }\n\n        return (false, 0, \"\");\n    }\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/token/ERC721/ERC721Upgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\nimport \"../../utils/ContextUpgradeable.sol\";\nimport \"./IERC721Upgradeable.sol\";\nimport \"./IERC721MetadataUpgradeable.sol\";\nimport \"./IERC721EnumerableUpgradeable.sol\";\nimport \"./IERC721ReceiverUpgradeable.sol\";\nimport \"../../introspection/ERC165Upgradeable.sol\";\nimport \"../../math/SafeMathUpgradeable.sol\";\nimport \"../../utils/AddressUpgradeable.sol\";\nimport \"../../utils/EnumerableSetUpgradeable.sol\";\nimport \"../../utils/EnumerableMapUpgradeable.sol\";\nimport \"../../utils/StringsUpgradeable.sol\";\nimport \"../../proxy/Initializable.sol\";\n\n/**\n * @title ERC721 Non-Fungible Token Standard basic implementation\n * @dev see https://eips.ethereum.org/EIPS/eip-721\n */\ncontract ERC721Upgradeable is Initializable, ContextUpgradeable, ERC165Upgradeable, IERC721Upgradeable, IERC721MetadataUpgradeable, IERC721EnumerableUpgradeable {\n    using SafeMathUpgradeable for uint256;\n    using AddressUpgradeable for address;\n    using EnumerableSetUpgradeable for EnumerableSetUpgradeable.UintSet;\n    using EnumerableMapUpgradeable for EnumerableMapUpgradeable.UintToAddressMap;\n    using StringsUpgradeable for uint256;\n\n    // Equals to `bytes4(keccak256(\"onERC721Received(address,address,uint256,bytes)\"))`\n    // which can be also obtained as `IERC721Receiver(0).onERC721Received.selector`\n    bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;\n\n    // Mapping from holder address to their (enumerable) set of owned tokens\n    mapping (address => EnumerableSetUpgradeable.UintSet) private _holderTokens;\n\n    // Enumerable mapping from token ids to their owners\n    EnumerableMapUpgradeable.UintToAddressMap private _tokenOwners;\n\n    // Mapping from token ID to approved address\n    mapping (uint256 => address) private _tokenApprovals;\n\n    // Mapping from owner to operator approvals\n    mapping (address => mapping (address => bool)) private _operatorApprovals;\n\n    // Token name\n    string private _name;\n\n    // Token symbol\n    string private _symbol;\n\n    // Optional mapping for token URIs\n    mapping (uint256 => string) private _tokenURIs;\n\n    // Base URI\n    string private _baseURI;\n\n    /*\n     *     bytes4(keccak256('balanceOf(address)')) == 0x70a08231\n     *     bytes4(keccak256('ownerOf(uint256)')) == 0x6352211e\n     *     bytes4(keccak256('approve(address,uint256)')) == 0x095ea7b3\n     *     bytes4(keccak256('getApproved(uint256)')) == 0x081812fc\n     *     bytes4(keccak256('setApprovalForAll(address,bool)')) == 0xa22cb465\n     *     bytes4(keccak256('isApprovedForAll(address,address)')) == 0xe985e9c5\n     *     bytes4(keccak256('transferFrom(address,address,uint256)')) == 0x23b872dd\n     *     bytes4(keccak256('safeTransferFrom(address,address,uint256)')) == 0x42842e0e\n     *     bytes4(keccak256('safeTransferFrom(address,address,uint256,bytes)')) == 0xb88d4fde\n     *\n     *     => 0x70a08231 ^ 0x6352211e ^ 0x095ea7b3 ^ 0x081812fc ^\n     *        0xa22cb465 ^ 0xe985e9c5 ^ 0x23b872dd ^ 0x42842e0e ^ 0xb88d4fde == 0x80ac58cd\n     */\n    bytes4 private constant _INTERFACE_ID_ERC721 = 0x80ac58cd;\n\n    /*\n     *     bytes4(keccak256('name()')) == 0x06fdde03\n     *     bytes4(keccak256('symbol()')) == 0x95d89b41\n     *     bytes4(keccak256('tokenURI(uint256)')) == 0xc87b56dd\n     *\n     *     => 0x06fdde03 ^ 0x95d89b41 ^ 0xc87b56dd == 0x5b5e139f\n     */\n    bytes4 private constant _INTERFACE_ID_ERC721_METADATA = 0x5b5e139f;\n\n    /*\n     *     bytes4(keccak256('totalSupply()')) == 0x18160ddd\n     *     bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) == 0x2f745c59\n     *     bytes4(keccak256('tokenByIndex(uint256)')) == 0x4f6ccce7\n     *\n     *     => 0x18160ddd ^ 0x2f745c59 ^ 0x4f6ccce7 == 0x780e9d63\n     */\n    bytes4 private constant _INTERFACE_ID_ERC721_ENUMERABLE = 0x780e9d63;\n\n    /**\n     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.\n     */\n    function __ERC721_init(string memory name_, string memory symbol_) internal initializer {\n        __Context_init_unchained();\n        __ERC165_init_unchained();\n        __ERC721_init_unchained(name_, symbol_);\n    }\n\n    function __ERC721_init_unchained(string memory name_, string memory symbol_) internal initializer {\n        _name = name_;\n        _symbol = symbol_;\n\n        // register the supported interfaces to conform to ERC721 via ERC165\n        _registerInterface(_INTERFACE_ID_ERC721);\n        _registerInterface(_INTERFACE_ID_ERC721_METADATA);\n        _registerInterface(_INTERFACE_ID_ERC721_ENUMERABLE);\n    }\n\n    /**\n     * @dev See {IERC721-balanceOf}.\n     */\n    function balanceOf(address owner) public view virtual override returns (uint256) {\n        require(owner != address(0), \"ERC721: balance query for the zero address\");\n        return _holderTokens[owner].length();\n    }\n\n    /**\n     * @dev See {IERC721-ownerOf}.\n     */\n    function ownerOf(uint256 tokenId) public view virtual override returns (address) {\n        return _tokenOwners.get(tokenId, \"ERC721: owner query for nonexistent token\");\n    }\n\n    /**\n     * @dev See {IERC721Metadata-name}.\n     */\n    function name() public view virtual override returns (string memory) {\n        return _name;\n    }\n\n    /**\n     * @dev See {IERC721Metadata-symbol}.\n     */\n    function symbol() public view virtual override returns (string memory) {\n        return _symbol;\n    }\n\n    /**\n     * @dev See {IERC721Metadata-tokenURI}.\n     */\n    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {\n        require(_exists(tokenId), \"ERC721Metadata: URI query for nonexistent token\");\n\n        string memory _tokenURI = _tokenURIs[tokenId];\n        string memory base = baseURI();\n\n        // If there is no base URI, return the token URI.\n        if (bytes(base).length == 0) {\n            return _tokenURI;\n        }\n        // If both are set, concatenate the baseURI and tokenURI (via abi.encodePacked).\n        if (bytes(_tokenURI).length > 0) {\n            return string(abi.encodePacked(base, _tokenURI));\n        }\n        // If there is a baseURI but no tokenURI, concatenate the tokenID to the baseURI.\n        return string(abi.encodePacked(base, tokenId.toString()));\n    }\n\n    /**\n    * @dev Returns the base URI set via {_setBaseURI}. This will be\n    * automatically added as a prefix in {tokenURI} to each token's URI, or\n    * to the token ID if no specific URI is set for that token ID.\n    */\n    function baseURI() public view virtual returns (string memory) {\n        return _baseURI;\n    }\n\n    /**\n     * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.\n     */\n    function tokenOfOwnerByIndex(address owner, uint256 index) public view virtual override returns (uint256) {\n        return _holderTokens[owner].at(index);\n    }\n\n    /**\n     * @dev See {IERC721Enumerable-totalSupply}.\n     */\n    function totalSupply() public view virtual override returns (uint256) {\n        // _tokenOwners are indexed by tokenIds, so .length() returns the number of tokenIds\n        return _tokenOwners.length();\n    }\n\n    /**\n     * @dev See {IERC721Enumerable-tokenByIndex}.\n     */\n    function tokenByIndex(uint256 index) public view virtual override returns (uint256) {\n        (uint256 tokenId, ) = _tokenOwners.at(index);\n        return tokenId;\n    }\n\n    /**\n     * @dev See {IERC721-approve}.\n     */\n    function approve(address to, uint256 tokenId) public virtual override {\n        address owner = ERC721Upgradeable.ownerOf(tokenId);\n        require(to != owner, \"ERC721: approval to current owner\");\n\n        require(_msgSender() == owner || ERC721Upgradeable.isApprovedForAll(owner, _msgSender()),\n            \"ERC721: approve caller is not owner nor approved for all\"\n        );\n\n        _approve(to, tokenId);\n    }\n\n    /**\n     * @dev See {IERC721-getApproved}.\n     */\n    function getApproved(uint256 tokenId) public view virtual override returns (address) {\n        require(_exists(tokenId), \"ERC721: approved query for nonexistent token\");\n\n        return _tokenApprovals[tokenId];\n    }\n\n    /**\n     * @dev See {IERC721-setApprovalForAll}.\n     */\n    function setApprovalForAll(address operator, bool approved) public virtual override {\n        require(operator != _msgSender(), \"ERC721: approve to caller\");\n\n        _operatorApprovals[_msgSender()][operator] = approved;\n        emit ApprovalForAll(_msgSender(), operator, approved);\n    }\n\n    /**\n     * @dev See {IERC721-isApprovedForAll}.\n     */\n    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {\n        return _operatorApprovals[owner][operator];\n    }\n\n    /**\n     * @dev See {IERC721-transferFrom}.\n     */\n    function transferFrom(address from, address to, uint256 tokenId) public virtual override {\n        //solhint-disable-next-line max-line-length\n        require(_isApprovedOrOwner(_msgSender(), tokenId), \"ERC721: transfer caller is not owner nor approved\");\n\n        _transfer(from, to, tokenId);\n    }\n\n    /**\n     * @dev See {IERC721-safeTransferFrom}.\n     */\n    function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override {\n        safeTransferFrom(from, to, tokenId, \"\");\n    }\n\n    /**\n     * @dev See {IERC721-safeTransferFrom}.\n     */\n    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public virtual override {\n        require(_isApprovedOrOwner(_msgSender(), tokenId), \"ERC721: transfer caller is not owner nor approved\");\n        _safeTransfer(from, to, tokenId, _data);\n    }\n\n    /**\n     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients\n     * are aware of the ERC721 protocol to prevent tokens from being forever locked.\n     *\n     * `_data` is additional data, it has no specified format and it is sent in call to `to`.\n     *\n     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.\n     * implement alternative mechanisms to perform token transfer, such as signature-based.\n     *\n     * Requirements:\n     *\n     * - `from` cannot be the zero address.\n     * - `to` cannot be the zero address.\n     * - `tokenId` token must exist and be owned by `from`.\n     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\n     *\n     * Emits a {Transfer} event.\n     */\n    function _safeTransfer(address from, address to, uint256 tokenId, bytes memory _data) internal virtual {\n        _transfer(from, to, tokenId);\n        require(_checkOnERC721Received(from, to, tokenId, _data), \"ERC721: transfer to non ERC721Receiver implementer\");\n    }\n\n    /**\n     * @dev Returns whether `tokenId` exists.\n     *\n     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.\n     *\n     * Tokens start existing when they are minted (`_mint`),\n     * and stop existing when they are burned (`_burn`).\n     */\n    function _exists(uint256 tokenId) internal view virtual returns (bool) {\n        return _tokenOwners.contains(tokenId);\n    }\n\n    /**\n     * @dev Returns whether `spender` is allowed to manage `tokenId`.\n     *\n     * Requirements:\n     *\n     * - `tokenId` must exist.\n     */\n    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {\n        require(_exists(tokenId), \"ERC721: operator query for nonexistent token\");\n        address owner = ERC721Upgradeable.ownerOf(tokenId);\n        return (spender == owner || getApproved(tokenId) == spender || ERC721Upgradeable.isApprovedForAll(owner, spender));\n    }\n\n    /**\n     * @dev Safely mints `tokenId` and transfers it to `to`.\n     *\n     * Requirements:\n     d*\n     * - `tokenId` must not exist.\n     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\n     *\n     * Emits a {Transfer} event.\n     */\n    function _safeMint(address to, uint256 tokenId) internal virtual {\n        _safeMint(to, tokenId, \"\");\n    }\n\n    /**\n     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is\n     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.\n     */\n    function _safeMint(address to, uint256 tokenId, bytes memory _data) internal virtual {\n        _mint(to, tokenId);\n        require(_checkOnERC721Received(address(0), to, tokenId, _data), \"ERC721: transfer to non ERC721Receiver implementer\");\n    }\n\n    /**\n     * @dev Mints `tokenId` and transfers it to `to`.\n     *\n     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible\n     *\n     * Requirements:\n     *\n     * - `tokenId` must not exist.\n     * - `to` cannot be the zero address.\n     *\n     * Emits a {Transfer} event.\n     */\n    function _mint(address to, uint256 tokenId) internal virtual {\n        require(to != address(0), \"ERC721: mint to the zero address\");\n        require(!_exists(tokenId), \"ERC721: token already minted\");\n\n        _beforeTokenTransfer(address(0), to, tokenId);\n\n        _holderTokens[to].add(tokenId);\n\n        _tokenOwners.set(tokenId, to);\n\n        emit Transfer(address(0), to, tokenId);\n    }\n\n    /**\n     * @dev Destroys `tokenId`.\n     * The approval is cleared when the token is burned.\n     *\n     * Requirements:\n     *\n     * - `tokenId` must exist.\n     *\n     * Emits a {Transfer} event.\n     */\n    function _burn(uint256 tokenId) internal virtual {\n        address owner = ERC721Upgradeable.ownerOf(tokenId); // internal owner\n\n        _beforeTokenTransfer(owner, address(0), tokenId);\n\n        // Clear approvals\n        _approve(address(0), tokenId);\n\n        // Clear metadata (if any)\n        if (bytes(_tokenURIs[tokenId]).length != 0) {\n            delete _tokenURIs[tokenId];\n        }\n\n        _holderTokens[owner].remove(tokenId);\n\n        _tokenOwners.remove(tokenId);\n\n        emit Transfer(owner, address(0), tokenId);\n    }\n\n    /**\n     * @dev Transfers `tokenId` from `from` to `to`.\n     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.\n     *\n     * Requirements:\n     *\n     * - `to` cannot be the zero address.\n     * - `tokenId` token must be owned by `from`.\n     *\n     * Emits a {Transfer} event.\n     */\n    function _transfer(address from, address to, uint256 tokenId) internal virtual {\n        require(ERC721Upgradeable.ownerOf(tokenId) == from, \"ERC721: transfer of token that is not own\"); // internal owner\n        require(to != address(0), \"ERC721: transfer to the zero address\");\n\n        _beforeTokenTransfer(from, to, tokenId);\n\n        // Clear approvals from the previous owner\n        _approve(address(0), tokenId);\n\n        _holderTokens[from].remove(tokenId);\n        _holderTokens[to].add(tokenId);\n\n        _tokenOwners.set(tokenId, to);\n\n        emit Transfer(from, to, tokenId);\n    }\n\n    /**\n     * @dev Sets `_tokenURI` as the tokenURI of `tokenId`.\n     *\n     * Requirements:\n     *\n     * - `tokenId` must exist.\n     */\n    function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {\n        require(_exists(tokenId), \"ERC721Metadata: URI set of nonexistent token\");\n        _tokenURIs[tokenId] = _tokenURI;\n    }\n\n    /**\n     * @dev Internal function to set the base URI for all token IDs. It is\n     * automatically added as a prefix to the value returned in {tokenURI},\n     * or to the token ID if {tokenURI} is empty.\n     */\n    function _setBaseURI(string memory baseURI_) internal virtual {\n        _baseURI = baseURI_;\n    }\n\n    /**\n     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.\n     * The call is not executed if the target address is not a contract.\n     *\n     * @param from address representing the previous owner of the given token ID\n     * @param to target address that will receive the tokens\n     * @param tokenId uint256 ID of the token to be transferred\n     * @param _data bytes optional data to send along with the call\n     * @return bool whether the call correctly returned the expected magic value\n     */\n    function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data)\n        private returns (bool)\n    {\n        if (!to.isContract()) {\n            return true;\n        }\n        bytes memory returndata = to.functionCall(abi.encodeWithSelector(\n            IERC721ReceiverUpgradeable(to).onERC721Received.selector,\n            _msgSender(),\n            from,\n            tokenId,\n            _data\n        ), \"ERC721: transfer to non ERC721Receiver implementer\");\n        bytes4 retval = abi.decode(returndata, (bytes4));\n        return (retval == _ERC721_RECEIVED);\n    }\n\n    /**\n     * @dev Approve `to` to operate on `tokenId`\n     *\n     * Emits an {Approval} event.\n     */\n    function _approve(address to, uint256 tokenId) internal virtual {\n        _tokenApprovals[tokenId] = to;\n        emit Approval(ERC721Upgradeable.ownerOf(tokenId), to, tokenId); // internal owner\n    }\n\n    /**\n     * @dev Hook that is called before any token transfer. This includes minting\n     * and burning.\n     *\n     * Calling conditions:\n     *\n     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be\n     * transferred to `to`.\n     * - When `from` is zero, `tokenId` will be minted for `to`.\n     * - When `to` is zero, ``from``'s `tokenId` will be burned.\n     * - `from` cannot be the zero address.\n     * - `to` cannot be the zero address.\n     *\n     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].\n     */\n    function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual { }\n    uint256[41] private __gap;\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/token/ERC721/ERC721BurnableUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\nimport \"../../utils/ContextUpgradeable.sol\";\nimport \"./ERC721Upgradeable.sol\";\nimport \"../../proxy/Initializable.sol\";\n\n/**\n * @title ERC721 Burnable Token\n * @dev ERC721 Token that can be irreversibly burned (destroyed).\n */\nabstract contract ERC721BurnableUpgradeable is Initializable, ContextUpgradeable, ERC721Upgradeable {\n    function __ERC721Burnable_init() internal initializer {\n        __Context_init_unchained();\n        __ERC165_init_unchained();\n        __ERC721Burnable_init_unchained();\n    }\n\n    function __ERC721Burnable_init_unchained() internal initializer {\n    }\n    /**\n     * @dev Burns `tokenId`. See {ERC721-_burn}.\n     *\n     * Requirements:\n     *\n     * - The caller must own `tokenId` or be an approved operator.\n     */\n    function burn(uint256 tokenId) public virtual {\n        //solhint-disable-next-line max-line-length\n        require(_isApprovedOrOwner(_msgSender(), tokenId), \"ERC721Burnable: caller is not owner nor approved\");\n        _burn(tokenId);\n    }\n    uint256[50] private __gap;\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/introspection/ERC165Upgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\nimport \"./IERC165Upgradeable.sol\";\nimport \"../proxy/Initializable.sol\";\n\n/**\n * @dev Implementation of the {IERC165} interface.\n *\n * Contracts may inherit from this and call {_registerInterface} to declare\n * their support of an interface.\n */\nabstract contract ERC165Upgradeable is Initializable, IERC165Upgradeable {\n    /*\n     * bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7\n     */\n    bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;\n\n    /**\n     * @dev Mapping of interface ids to whether or not it's supported.\n     */\n    mapping(bytes4 => bool) private _supportedInterfaces;\n\n    function __ERC165_init() internal initializer {\n        __ERC165_init_unchained();\n    }\n\n    function __ERC165_init_unchained() internal initializer {\n        // Derived contracts need only register support for their own interfaces,\n        // we register support for ERC165 itself here\n        _registerInterface(_INTERFACE_ID_ERC165);\n    }\n\n    /**\n     * @dev See {IERC165-supportsInterface}.\n     *\n     * Time complexity O(1), guaranteed to always use less than 30 000 gas.\n     */\n    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {\n        return _supportedInterfaces[interfaceId];\n    }\n\n    /**\n     * @dev Registers the contract as an implementer of the interface defined by\n     * `interfaceId`. Support of the actual ERC165 interface is automatic and\n     * registering its interface id is not required.\n     *\n     * See {IERC165-supportsInterface}.\n     *\n     * Requirements:\n     *\n     * - `interfaceId` cannot be the ERC165 invalid interface (`0xffffffff`).\n     */\n    function _registerInterface(bytes4 interfaceId) internal virtual {\n        require(interfaceId != 0xffffffff, \"ERC165: invalid interface id\");\n        _supportedInterfaces[interfaceId] = true;\n    }\n    uint256[49] private __gap;\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/access/OwnableUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\nimport \"../utils/ContextUpgradeable.sol\";\nimport \"../proxy/Initializable.sol\";\n/**\n * @dev Contract module which provides a basic access control mechanism, where\n * there is an account (an owner) that can be granted exclusive access to\n * specific functions.\n *\n * By default, the owner account will be the one that deploys the contract. This\n * can later be changed with {transferOwnership}.\n *\n * This module is used through inheritance. It will make available the modifier\n * `onlyOwner`, which can be applied to your functions to restrict their use to\n * the owner.\n */\nabstract contract OwnableUpgradeable is Initializable, ContextUpgradeable {\n    address private _owner;\n\n    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);\n\n    /**\n     * @dev Initializes the contract setting the deployer as the initial owner.\n     */\n    function __Ownable_init() internal initializer {\n        __Context_init_unchained();\n        __Ownable_init_unchained();\n    }\n\n    function __Ownable_init_unchained() internal initializer {\n        address msgSender = _msgSender();\n        _owner = msgSender;\n        emit OwnershipTransferred(address(0), msgSender);\n    }\n\n    /**\n     * @dev Returns the address of the current owner.\n     */\n    function owner() public view virtual returns (address) {\n        return _owner;\n    }\n\n    /**\n     * @dev Throws if called by any account other than the owner.\n     */\n    modifier onlyOwner() {\n        require(owner() == _msgSender(), \"Ownable: caller is not the owner\");\n        _;\n    }\n\n    /**\n     * @dev Leaves the contract without owner. It will not be possible to call\n     * `onlyOwner` functions anymore. Can only be called by the current owner.\n     *\n     * NOTE: Renouncing ownership will leave the contract without an owner,\n     * thereby removing any functionality that is only available to the owner.\n     */\n    function renounceOwnership() public virtual onlyOwner {\n        emit OwnershipTransferred(_owner, address(0));\n        _owner = address(0);\n    }\n\n    /**\n     * @dev Transfers ownership of the contract to a new account (`newOwner`).\n     * Can only be called by the current owner.\n     */\n    function transferOwnership(address newOwner) public virtual onlyOwner {\n        require(newOwner != address(0), \"Ownable: new owner is the zero address\");\n        emit OwnershipTransferred(_owner, newOwner);\n        _owner = newOwner;\n    }\n    uint256[49] private __gap;\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/utils/CountersUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\nimport \"../math/SafeMathUpgradeable.sol\";\n\n/**\n * @title Counters\n * @author Matt Condon (@shrugs)\n * @dev Provides counters that can only be incremented or decremented by one. This can be used e.g. to track the number\n * of elements in a mapping, issuing ERC721 ids, or counting request ids.\n *\n * Include with `using Counters for Counters.Counter;`\n * Since it is not possible to overflow a 256 bit integer with increments of one, `increment` can skip the {SafeMath}\n * overflow check, thereby saving gas. This does assume however correct usage, in that the underlying `_value` is never\n * directly accessed.\n */\nlibrary CountersUpgradeable {\n    using SafeMathUpgradeable for uint256;\n\n    struct Counter {\n        // This variable should never be directly accessed by users of the library: interactions must be restricted to\n        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add\n        // this feature: see https://github.com/ethereum/solidity/issues/4637\n        uint256 _value; // default: 0\n    }\n\n    function current(Counter storage counter) internal view returns (uint256) {\n        return counter._value;\n    }\n\n    function increment(Counter storage counter) internal {\n        // The {SafeMath} overflow check can be skipped here, see the comment at the top\n        counter._value += 1;\n    }\n\n    function decrement(Counter storage counter) internal {\n        counter._value = counter._value.sub(1);\n    }\n}\n"
    },
    "contracts/token/ERC721/IERC721Creator.sol": {
      "content": "// contracts/token/ERC721/IERC721Creator.sol\n// SPDX-License-Identifier: MIT\npragma solidity 0.7.3;\n\n/**\n * @title IERC721 Non-Fungible Token Creator basic interface\n */\nabstract contract IERC721Creator {\n    /**\n     * @dev Gets the creator of the token\n     * @param _tokenId uint256 ID of the token\n     * @return address of the creator\n     */\n    function tokenCreator(uint256 _tokenId)\n        public\n        view\n        virtual\n        returns (address payable);\n\n    function calcIERC721CreatorInterfaceId() public pure returns (bytes4) {\n        return this.tokenCreator.selector;\n    }\n}\n"
    },
    "contracts/royalty/ERC2981Upgradeable.sol": {
      "content": "// contracts/royalty/ERC2981.sol\n// SPDX-License-Identifier: MIT\npragma solidity 0.7.3;\n\nimport \"@openzeppelin/contracts-upgradeable-0.7.2/introspection/ERC165Upgradeable.sol\";\nimport \"@openzeppelin/contracts-upgradeable-0.7.2/math/SafeMathUpgradeable.sol\";\nimport \"./IERC2981.sol\";\n\nabstract contract ERC2981Upgradeable is IERC2981, ERC165Upgradeable {\n    using SafeMathUpgradeable for uint256;\n\n    // bytes4(keccak256(\"royaltyInfo(uint256,uint256)\")) == 0x2a55205a\n    bytes4 private constant _INTERFACE_ID_ERC2981 = 0x2a55205a;\n\n    address public defaultRoyaltyReceiver;\n\n    mapping(uint256 => address) royaltyReceivers;\n    mapping(uint256 => uint256) royaltyPercentages;\n\n    constructor() {}\n\n    function __ERC2981__init() internal initializer {\n        __ERC165_init();\n        _registerInterface(_INTERFACE_ID_ERC2981);\n    }\n\n    function royaltyInfo(uint256 _tokenId, uint256 _salePrice)\n        public\n        view\n        virtual\n        override\n        returns (address receiver, uint256 royaltyAmount)\n    {\n        receiver = royaltyReceivers[_tokenId] != address(0)\n            ? royaltyReceivers[_tokenId]\n            : defaultRoyaltyReceiver;\n        royaltyAmount = _salePrice.mul(royaltyPercentages[_tokenId]).div(100);\n    }\n\n    function _setDefaultRoyaltyReceiver(address _receiver) internal {\n        defaultRoyaltyReceiver = _receiver;\n    }\n\n    function _setRoyaltyReceiver(uint256 _tokenId, address _newReceiver)\n        internal\n    {\n        royaltyReceivers[_tokenId] = _newReceiver;\n    }\n\n    function _setRoyaltyPercentage(uint256 _tokenId, uint256 _percentage)\n        internal\n    {\n        royaltyPercentages[_tokenId] = _percentage;\n    }\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/utils/ContextUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity >=0.6.0 <0.8.0;\nimport \"../proxy/Initializable.sol\";\n\n/*\n * @dev Provides information about the current execution context, including the\n * sender of the transaction and its data. While these are generally available\n * via msg.sender and msg.data, they should not be accessed in such a direct\n * manner, since when dealing with GSN meta-transactions the account sending and\n * paying for execution may not be the actual sender (as far as an application\n * is concerned).\n *\n * This contract is only required for intermediate, library-like contracts.\n */\nabstract contract ContextUpgradeable is Initializable {\n    function __Context_init() internal initializer {\n        __Context_init_unchained();\n    }\n\n    function __Context_init_unchained() internal initializer {\n    }\n    function _msgSender() internal view virtual returns (address payable) {\n        return msg.sender;\n    }\n\n    function _msgData() internal view virtual returns (bytes memory) {\n        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691\n        return msg.data;\n    }\n    uint256[50] private __gap;\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/token/ERC721/IERC721Upgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\nimport \"../../introspection/IERC165Upgradeable.sol\";\n\n/**\n * @dev Required interface of an ERC721 compliant contract.\n */\ninterface IERC721Upgradeable is IERC165Upgradeable {\n    /**\n     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.\n     */\n    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);\n\n    /**\n     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.\n     */\n    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);\n\n    /**\n     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.\n     */\n    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);\n\n    /**\n     * @dev Returns the number of tokens in ``owner``'s account.\n     */\n    function balanceOf(address owner) external view returns (uint256 balance);\n\n    /**\n     * @dev Returns the owner of the `tokenId` token.\n     *\n     * Requirements:\n     *\n     * - `tokenId` must exist.\n     */\n    function ownerOf(uint256 tokenId) external view returns (address owner);\n\n    /**\n     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients\n     * are aware of the ERC721 protocol to prevent tokens from being forever locked.\n     *\n     * Requirements:\n     *\n     * - `from` cannot be the zero address.\n     * - `to` cannot be the zero address.\n     * - `tokenId` token must exist and be owned by `from`.\n     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.\n     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\n     *\n     * Emits a {Transfer} event.\n     */\n    function safeTransferFrom(address from, address to, uint256 tokenId) external;\n\n    /**\n     * @dev Transfers `tokenId` token from `from` to `to`.\n     *\n     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.\n     *\n     * Requirements:\n     *\n     * - `from` cannot be the zero address.\n     * - `to` cannot be the zero address.\n     * - `tokenId` token must be owned by `from`.\n     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.\n     *\n     * Emits a {Transfer} event.\n     */\n    function transferFrom(address from, address to, uint256 tokenId) external;\n\n    /**\n     * @dev Gives permission to `to` to transfer `tokenId` token to another account.\n     * The approval is cleared when the token is transferred.\n     *\n     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.\n     *\n     * Requirements:\n     *\n     * - The caller must own the token or be an approved operator.\n     * - `tokenId` must exist.\n     *\n     * Emits an {Approval} event.\n     */\n    function approve(address to, uint256 tokenId) external;\n\n    /**\n     * @dev Returns the account approved for `tokenId` token.\n     *\n     * Requirements:\n     *\n     * - `tokenId` must exist.\n     */\n    function getApproved(uint256 tokenId) external view returns (address operator);\n\n    /**\n     * @dev Approve or remove `operator` as an operator for the caller.\n     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.\n     *\n     * Requirements:\n     *\n     * - The `operator` cannot be the caller.\n     *\n     * Emits an {ApprovalForAll} event.\n     */\n    function setApprovalForAll(address operator, bool _approved) external;\n\n    /**\n     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.\n     *\n     * See {setApprovalForAll}\n     */\n    function isApprovedForAll(address owner, address operator) external view returns (bool);\n\n    /**\n      * @dev Safely transfers `tokenId` token from `from` to `to`.\n      *\n      * Requirements:\n      *\n      * - `from` cannot be the zero address.\n      * - `to` cannot be the zero address.\n      * - `tokenId` token must exist and be owned by `from`.\n      * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.\n      * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\n      *\n      * Emits a {Transfer} event.\n      */\n    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/token/ERC721/IERC721MetadataUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\nimport \"./IERC721Upgradeable.sol\";\n\n/**\n * @title ERC-721 Non-Fungible Token Standard, optional metadata extension\n * @dev See https://eips.ethereum.org/EIPS/eip-721\n */\ninterface IERC721MetadataUpgradeable is IERC721Upgradeable {\n\n    /**\n     * @dev Returns the token collection name.\n     */\n    function name() external view returns (string memory);\n\n    /**\n     * @dev Returns the token collection symbol.\n     */\n    function symbol() external view returns (string memory);\n\n    /**\n     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.\n     */\n    function tokenURI(uint256 tokenId) external view returns (string memory);\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/token/ERC721/IERC721EnumerableUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\nimport \"./IERC721Upgradeable.sol\";\n\n/**\n * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension\n * @dev See https://eips.ethereum.org/EIPS/eip-721\n */\ninterface IERC721EnumerableUpgradeable is IERC721Upgradeable {\n\n    /**\n     * @dev Returns the total amount of tokens stored by the contract.\n     */\n    function totalSupply() external view returns (uint256);\n\n    /**\n     * @dev Returns a token ID owned by `owner` at a given `index` of its token list.\n     * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.\n     */\n    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256 tokenId);\n\n    /**\n     * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.\n     * Use along with {totalSupply} to enumerate all tokens.\n     */\n    function tokenByIndex(uint256 index) external view returns (uint256);\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/token/ERC721/IERC721ReceiverUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\n/**\n * @title ERC721 token receiver interface\n * @dev Interface for any contract that wants to support safeTransfers\n * from ERC721 asset contracts.\n */\ninterface IERC721ReceiverUpgradeable {\n    /**\n     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}\n     * by `operator` from `from`, this function is called.\n     *\n     * It must return its Solidity selector to confirm the token transfer.\n     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.\n     *\n     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.\n     */\n    function onERC721Received(address operator, address from, uint256 tokenId, bytes calldata data) external returns (bytes4);\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/math/SafeMathUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\n/**\n * @dev Wrappers over Solidity's arithmetic operations with added overflow\n * checks.\n *\n * Arithmetic operations in Solidity wrap on overflow. This can easily result\n * in bugs, because programmers usually assume that an overflow raises an\n * error, which is the standard behavior in high level programming languages.\n * `SafeMath` restores this intuition by reverting the transaction when an\n * operation overflows.\n *\n * Using this library instead of the unchecked operations eliminates an entire\n * class of bugs, so it's recommended to use it always.\n */\nlibrary SafeMathUpgradeable {\n    /**\n     * @dev Returns the addition of two unsigned integers, with an overflow flag.\n     *\n     * _Available since v3.4._\n     */\n    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {\n        uint256 c = a + b;\n        if (c < a) return (false, 0);\n        return (true, c);\n    }\n\n    /**\n     * @dev Returns the substraction of two unsigned integers, with an overflow flag.\n     *\n     * _Available since v3.4._\n     */\n    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {\n        if (b > a) return (false, 0);\n        return (true, a - b);\n    }\n\n    /**\n     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.\n     *\n     * _Available since v3.4._\n     */\n    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {\n        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the\n        // benefit is lost if 'b' is also tested.\n        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522\n        if (a == 0) return (true, 0);\n        uint256 c = a * b;\n        if (c / a != b) return (false, 0);\n        return (true, c);\n    }\n\n    /**\n     * @dev Returns the division of two unsigned integers, with a division by zero flag.\n     *\n     * _Available since v3.4._\n     */\n    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {\n        if (b == 0) return (false, 0);\n        return (true, a / b);\n    }\n\n    /**\n     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.\n     *\n     * _Available since v3.4._\n     */\n    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {\n        if (b == 0) return (false, 0);\n        return (true, a % b);\n    }\n\n    /**\n     * @dev Returns the addition of two unsigned integers, reverting on\n     * overflow.\n     *\n     * Counterpart to Solidity's `+` operator.\n     *\n     * Requirements:\n     *\n     * - Addition cannot overflow.\n     */\n    function add(uint256 a, uint256 b) internal pure returns (uint256) {\n        uint256 c = a + b;\n        require(c >= a, \"SafeMath: addition overflow\");\n        return c;\n    }\n\n    /**\n     * @dev Returns the subtraction of two unsigned integers, reverting on\n     * overflow (when the result is negative).\n     *\n     * Counterpart to Solidity's `-` operator.\n     *\n     * Requirements:\n     *\n     * - Subtraction cannot overflow.\n     */\n    function sub(uint256 a, uint256 b) internal pure returns (uint256) {\n        require(b <= a, \"SafeMath: subtraction overflow\");\n        return a - b;\n    }\n\n    /**\n     * @dev Returns the multiplication of two unsigned integers, reverting on\n     * overflow.\n     *\n     * Counterpart to Solidity's `*` operator.\n     *\n     * Requirements:\n     *\n     * - Multiplication cannot overflow.\n     */\n    function mul(uint256 a, uint256 b) internal pure returns (uint256) {\n        if (a == 0) return 0;\n        uint256 c = a * b;\n        require(c / a == b, \"SafeMath: multiplication overflow\");\n        return c;\n    }\n\n    /**\n     * @dev Returns the integer division of two unsigned integers, reverting on\n     * division by zero. The result is rounded towards zero.\n     *\n     * Counterpart to Solidity's `/` operator. Note: this function uses a\n     * `revert` opcode (which leaves remaining gas untouched) while Solidity\n     * uses an invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function div(uint256 a, uint256 b) internal pure returns (uint256) {\n        require(b > 0, \"SafeMath: division by zero\");\n        return a / b;\n    }\n\n    /**\n     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),\n     * reverting when dividing by zero.\n     *\n     * Counterpart to Solidity's `%` operator. This function uses a `revert`\n     * opcode (which leaves remaining gas untouched) while Solidity uses an\n     * invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function mod(uint256 a, uint256 b) internal pure returns (uint256) {\n        require(b > 0, \"SafeMath: modulo by zero\");\n        return a % b;\n    }\n\n    /**\n     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on\n     * overflow (when the result is negative).\n     *\n     * CAUTION: This function is deprecated because it requires allocating memory for the error\n     * message unnecessarily. For custom revert reasons use {trySub}.\n     *\n     * Counterpart to Solidity's `-` operator.\n     *\n     * Requirements:\n     *\n     * - Subtraction cannot overflow.\n     */\n    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\n        require(b <= a, errorMessage);\n        return a - b;\n    }\n\n    /**\n     * @dev Returns the integer division of two unsigned integers, reverting with custom message on\n     * division by zero. The result is rounded towards zero.\n     *\n     * CAUTION: This function is deprecated because it requires allocating memory for the error\n     * message unnecessarily. For custom revert reasons use {tryDiv}.\n     *\n     * Counterpart to Solidity's `/` operator. Note: this function uses a\n     * `revert` opcode (which leaves remaining gas untouched) while Solidity\n     * uses an invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\n        require(b > 0, errorMessage);\n        return a / b;\n    }\n\n    /**\n     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),\n     * reverting with custom message when dividing by zero.\n     *\n     * CAUTION: This function is deprecated because it requires allocating memory for the error\n     * message unnecessarily. For custom revert reasons use {tryMod}.\n     *\n     * Counterpart to Solidity's `%` operator. This function uses a `revert`\n     * opcode (which leaves remaining gas untouched) while Solidity uses an\n     * invalid opcode to revert (consuming all remaining gas).\n     *\n     * Requirements:\n     *\n     * - The divisor cannot be zero.\n     */\n    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\n        require(b > 0, errorMessage);\n        return a % b;\n    }\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/utils/AddressUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\n/**\n * @dev Collection of functions related to the address type\n */\nlibrary AddressUpgradeable {\n    /**\n     * @dev Returns true if `account` is a contract.\n     *\n     * [IMPORTANT]\n     * ====\n     * It is unsafe to assume that an address for which this function returns\n     * false is an externally-owned account (EOA) and not a contract.\n     *\n     * Among others, `isContract` will return false for the following\n     * types of addresses:\n     *\n     *  - an externally-owned account\n     *  - a contract in construction\n     *  - an address where a contract will be created\n     *  - an address where a contract lived, but was destroyed\n     * ====\n     */\n    function isContract(address account) internal view returns (bool) {\n        // This method relies on extcodesize, which returns 0 for contracts in\n        // construction, since the code is only stored at the end of the\n        // constructor execution.\n\n        uint256 size;\n        // solhint-disable-next-line no-inline-assembly\n        assembly { size := extcodesize(account) }\n        return size > 0;\n    }\n\n    /**\n     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to\n     * `recipient`, forwarding all available gas and reverting on errors.\n     *\n     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost\n     * of certain opcodes, possibly making contracts go over the 2300 gas limit\n     * imposed by `transfer`, making them unable to receive funds via\n     * `transfer`. {sendValue} removes this limitation.\n     *\n     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].\n     *\n     * IMPORTANT: because control is transferred to `recipient`, care must be\n     * taken to not create reentrancy vulnerabilities. Consider using\n     * {ReentrancyGuard} or the\n     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].\n     */\n    function sendValue(address payable recipient, uint256 amount) internal {\n        require(address(this).balance >= amount, \"Address: insufficient balance\");\n\n        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value\n        (bool success, ) = recipient.call{ value: amount }(\"\");\n        require(success, \"Address: unable to send value, recipient may have reverted\");\n    }\n\n    /**\n     * @dev Performs a Solidity function call using a low level `call`. A\n     * plain`call` is an unsafe replacement for a function call: use this\n     * function instead.\n     *\n     * If `target` reverts with a revert reason, it is bubbled up by this\n     * function (like regular Solidity function calls).\n     *\n     * Returns the raw returned data. To convert to the expected return value,\n     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].\n     *\n     * Requirements:\n     *\n     * - `target` must be a contract.\n     * - calling `target` with `data` must not revert.\n     *\n     * _Available since v3.1._\n     */\n    function functionCall(address target, bytes memory data) internal returns (bytes memory) {\n      return functionCall(target, data, \"Address: low-level call failed\");\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with\n     * `errorMessage` as a fallback revert reason when `target` reverts.\n     *\n     * _Available since v3.1._\n     */\n    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {\n        return functionCallWithValue(target, data, 0, errorMessage);\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\n     * but also transferring `value` wei to `target`.\n     *\n     * Requirements:\n     *\n     * - the calling contract must have an ETH balance of at least `value`.\n     * - the called Solidity function must be `payable`.\n     *\n     * _Available since v3.1._\n     */\n    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {\n        return functionCallWithValue(target, data, value, \"Address: low-level call with value failed\");\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but\n     * with `errorMessage` as a fallback revert reason when `target` reverts.\n     *\n     * _Available since v3.1._\n     */\n    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {\n        require(address(this).balance >= value, \"Address: insufficient balance for call\");\n        require(isContract(target), \"Address: call to non-contract\");\n\n        // solhint-disable-next-line avoid-low-level-calls\n        (bool success, bytes memory returndata) = target.call{ value: value }(data);\n        return _verifyCallResult(success, returndata, errorMessage);\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],\n     * but performing a static call.\n     *\n     * _Available since v3.3._\n     */\n    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {\n        return functionStaticCall(target, data, \"Address: low-level static call failed\");\n    }\n\n    /**\n     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],\n     * but performing a static call.\n     *\n     * _Available since v3.3._\n     */\n    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {\n        require(isContract(target), \"Address: static call to non-contract\");\n\n        // solhint-disable-next-line avoid-low-level-calls\n        (bool success, bytes memory returndata) = target.staticcall(data);\n        return _verifyCallResult(success, returndata, errorMessage);\n    }\n\n    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {\n        if (success) {\n            return returndata;\n        } else {\n            // Look for revert reason and bubble it up if present\n            if (returndata.length > 0) {\n                // The easiest way to bubble the revert reason is using memory via assembly\n\n                // solhint-disable-next-line no-inline-assembly\n                assembly {\n                    let returndata_size := mload(returndata)\n                    revert(add(32, returndata), returndata_size)\n                }\n            } else {\n                revert(errorMessage);\n            }\n        }\n    }\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/utils/EnumerableSetUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\n/**\n * @dev Library for managing\n * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive\n * types.\n *\n * Sets have the following properties:\n *\n * - Elements are added, removed, and checked for existence in constant time\n * (O(1)).\n * - Elements are enumerated in O(n). No guarantees are made on the ordering.\n *\n * ```\n * contract Example {\n *     // Add the library methods\n *     using EnumerableSet for EnumerableSet.AddressSet;\n *\n *     // Declare a set state variable\n *     EnumerableSet.AddressSet private mySet;\n * }\n * ```\n *\n * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)\n * and `uint256` (`UintSet`) are supported.\n */\nlibrary EnumerableSetUpgradeable {\n    // To implement this library for multiple types with as little code\n    // repetition as possible, we write it in terms of a generic Set type with\n    // bytes32 values.\n    // The Set implementation uses private functions, and user-facing\n    // implementations (such as AddressSet) are just wrappers around the\n    // underlying Set.\n    // This means that we can only create new EnumerableSets for types that fit\n    // in bytes32.\n\n    struct Set {\n        // Storage of set values\n        bytes32[] _values;\n\n        // Position of the value in the `values` array, plus 1 because index 0\n        // means a value is not in the set.\n        mapping (bytes32 => uint256) _indexes;\n    }\n\n    /**\n     * @dev Add a value to a set. O(1).\n     *\n     * Returns true if the value was added to the set, that is if it was not\n     * already present.\n     */\n    function _add(Set storage set, bytes32 value) private returns (bool) {\n        if (!_contains(set, value)) {\n            set._values.push(value);\n            // The value is stored at length-1, but we add 1 to all indexes\n            // and use 0 as a sentinel value\n            set._indexes[value] = set._values.length;\n            return true;\n        } else {\n            return false;\n        }\n    }\n\n    /**\n     * @dev Removes a value from a set. O(1).\n     *\n     * Returns true if the value was removed from the set, that is if it was\n     * present.\n     */\n    function _remove(Set storage set, bytes32 value) private returns (bool) {\n        // We read and store the value's index to prevent multiple reads from the same storage slot\n        uint256 valueIndex = set._indexes[value];\n\n        if (valueIndex != 0) { // Equivalent to contains(set, value)\n            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in\n            // the array, and then remove the last element (sometimes called as 'swap and pop').\n            // This modifies the order of the array, as noted in {at}.\n\n            uint256 toDeleteIndex = valueIndex - 1;\n            uint256 lastIndex = set._values.length - 1;\n\n            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs\n            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.\n\n            bytes32 lastvalue = set._values[lastIndex];\n\n            // Move the last value to the index where the value to delete is\n            set._values[toDeleteIndex] = lastvalue;\n            // Update the index for the moved value\n            set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based\n\n            // Delete the slot where the moved value was stored\n            set._values.pop();\n\n            // Delete the index for the deleted slot\n            delete set._indexes[value];\n\n            return true;\n        } else {\n            return false;\n        }\n    }\n\n    /**\n     * @dev Returns true if the value is in the set. O(1).\n     */\n    function _contains(Set storage set, bytes32 value) private view returns (bool) {\n        return set._indexes[value] != 0;\n    }\n\n    /**\n     * @dev Returns the number of values on the set. O(1).\n     */\n    function _length(Set storage set) private view returns (uint256) {\n        return set._values.length;\n    }\n\n   /**\n    * @dev Returns the value stored at position `index` in the set. O(1).\n    *\n    * Note that there are no guarantees on the ordering of values inside the\n    * array, and it may change when more values are added or removed.\n    *\n    * Requirements:\n    *\n    * - `index` must be strictly less than {length}.\n    */\n    function _at(Set storage set, uint256 index) private view returns (bytes32) {\n        require(set._values.length > index, \"EnumerableSet: index out of bounds\");\n        return set._values[index];\n    }\n\n    // Bytes32Set\n\n    struct Bytes32Set {\n        Set _inner;\n    }\n\n    /**\n     * @dev Add a value to a set. O(1).\n     *\n     * Returns true if the value was added to the set, that is if it was not\n     * already present.\n     */\n    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {\n        return _add(set._inner, value);\n    }\n\n    /**\n     * @dev Removes a value from a set. O(1).\n     *\n     * Returns true if the value was removed from the set, that is if it was\n     * present.\n     */\n    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {\n        return _remove(set._inner, value);\n    }\n\n    /**\n     * @dev Returns true if the value is in the set. O(1).\n     */\n    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {\n        return _contains(set._inner, value);\n    }\n\n    /**\n     * @dev Returns the number of values in the set. O(1).\n     */\n    function length(Bytes32Set storage set) internal view returns (uint256) {\n        return _length(set._inner);\n    }\n\n   /**\n    * @dev Returns the value stored at position `index` in the set. O(1).\n    *\n    * Note that there are no guarantees on the ordering of values inside the\n    * array, and it may change when more values are added or removed.\n    *\n    * Requirements:\n    *\n    * - `index` must be strictly less than {length}.\n    */\n    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {\n        return _at(set._inner, index);\n    }\n\n    // AddressSet\n\n    struct AddressSet {\n        Set _inner;\n    }\n\n    /**\n     * @dev Add a value to a set. O(1).\n     *\n     * Returns true if the value was added to the set, that is if it was not\n     * already present.\n     */\n    function add(AddressSet storage set, address value) internal returns (bool) {\n        return _add(set._inner, bytes32(uint256(uint160(value))));\n    }\n\n    /**\n     * @dev Removes a value from a set. O(1).\n     *\n     * Returns true if the value was removed from the set, that is if it was\n     * present.\n     */\n    function remove(AddressSet storage set, address value) internal returns (bool) {\n        return _remove(set._inner, bytes32(uint256(uint160(value))));\n    }\n\n    /**\n     * @dev Returns true if the value is in the set. O(1).\n     */\n    function contains(AddressSet storage set, address value) internal view returns (bool) {\n        return _contains(set._inner, bytes32(uint256(uint160(value))));\n    }\n\n    /**\n     * @dev Returns the number of values in the set. O(1).\n     */\n    function length(AddressSet storage set) internal view returns (uint256) {\n        return _length(set._inner);\n    }\n\n   /**\n    * @dev Returns the value stored at position `index` in the set. O(1).\n    *\n    * Note that there are no guarantees on the ordering of values inside the\n    * array, and it may change when more values are added or removed.\n    *\n    * Requirements:\n    *\n    * - `index` must be strictly less than {length}.\n    */\n    function at(AddressSet storage set, uint256 index) internal view returns (address) {\n        return address(uint160(uint256(_at(set._inner, index))));\n    }\n\n\n    // UintSet\n\n    struct UintSet {\n        Set _inner;\n    }\n\n    /**\n     * @dev Add a value to a set. O(1).\n     *\n     * Returns true if the value was added to the set, that is if it was not\n     * already present.\n     */\n    function add(UintSet storage set, uint256 value) internal returns (bool) {\n        return _add(set._inner, bytes32(value));\n    }\n\n    /**\n     * @dev Removes a value from a set. O(1).\n     *\n     * Returns true if the value was removed from the set, that is if it was\n     * present.\n     */\n    function remove(UintSet storage set, uint256 value) internal returns (bool) {\n        return _remove(set._inner, bytes32(value));\n    }\n\n    /**\n     * @dev Returns true if the value is in the set. O(1).\n     */\n    function contains(UintSet storage set, uint256 value) internal view returns (bool) {\n        return _contains(set._inner, bytes32(value));\n    }\n\n    /**\n     * @dev Returns the number of values on the set. O(1).\n     */\n    function length(UintSet storage set) internal view returns (uint256) {\n        return _length(set._inner);\n    }\n\n   /**\n    * @dev Returns the value stored at position `index` in the set. O(1).\n    *\n    * Note that there are no guarantees on the ordering of values inside the\n    * array, and it may change when more values are added or removed.\n    *\n    * Requirements:\n    *\n    * - `index` must be strictly less than {length}.\n    */\n    function at(UintSet storage set, uint256 index) internal view returns (uint256) {\n        return uint256(_at(set._inner, index));\n    }\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/utils/EnumerableMapUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\n/**\n * @dev Library for managing an enumerable variant of Solidity's\n * https://solidity.readthedocs.io/en/latest/types.html#mapping-types[`mapping`]\n * type.\n *\n * Maps have the following properties:\n *\n * - Entries are added, removed, and checked for existence in constant time\n * (O(1)).\n * - Entries are enumerated in O(n). No guarantees are made on the ordering.\n *\n * ```\n * contract Example {\n *     // Add the library methods\n *     using EnumerableMap for EnumerableMap.UintToAddressMap;\n *\n *     // Declare a set state variable\n *     EnumerableMap.UintToAddressMap private myMap;\n * }\n * ```\n *\n * As of v3.0.0, only maps of type `uint256 -> address` (`UintToAddressMap`) are\n * supported.\n */\nlibrary EnumerableMapUpgradeable {\n    // To implement this library for multiple types with as little code\n    // repetition as possible, we write it in terms of a generic Map type with\n    // bytes32 keys and values.\n    // The Map implementation uses private functions, and user-facing\n    // implementations (such as Uint256ToAddressMap) are just wrappers around\n    // the underlying Map.\n    // This means that we can only create new EnumerableMaps for types that fit\n    // in bytes32.\n\n    struct MapEntry {\n        bytes32 _key;\n        bytes32 _value;\n    }\n\n    struct Map {\n        // Storage of map keys and values\n        MapEntry[] _entries;\n\n        // Position of the entry defined by a key in the `entries` array, plus 1\n        // because index 0 means a key is not in the map.\n        mapping (bytes32 => uint256) _indexes;\n    }\n\n    /**\n     * @dev Adds a key-value pair to a map, or updates the value for an existing\n     * key. O(1).\n     *\n     * Returns true if the key was added to the map, that is if it was not\n     * already present.\n     */\n    function _set(Map storage map, bytes32 key, bytes32 value) private returns (bool) {\n        // We read and store the key's index to prevent multiple reads from the same storage slot\n        uint256 keyIndex = map._indexes[key];\n\n        if (keyIndex == 0) { // Equivalent to !contains(map, key)\n            map._entries.push(MapEntry({ _key: key, _value: value }));\n            // The entry is stored at length-1, but we add 1 to all indexes\n            // and use 0 as a sentinel value\n            map._indexes[key] = map._entries.length;\n            return true;\n        } else {\n            map._entries[keyIndex - 1]._value = value;\n            return false;\n        }\n    }\n\n    /**\n     * @dev Removes a key-value pair from a map. O(1).\n     *\n     * Returns true if the key was removed from the map, that is if it was present.\n     */\n    function _remove(Map storage map, bytes32 key) private returns (bool) {\n        // We read and store the key's index to prevent multiple reads from the same storage slot\n        uint256 keyIndex = map._indexes[key];\n\n        if (keyIndex != 0) { // Equivalent to contains(map, key)\n            // To delete a key-value pair from the _entries array in O(1), we swap the entry to delete with the last one\n            // in the array, and then remove the last entry (sometimes called as 'swap and pop').\n            // This modifies the order of the array, as noted in {at}.\n\n            uint256 toDeleteIndex = keyIndex - 1;\n            uint256 lastIndex = map._entries.length - 1;\n\n            // When the entry to delete is the last one, the swap operation is unnecessary. However, since this occurs\n            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.\n\n            MapEntry storage lastEntry = map._entries[lastIndex];\n\n            // Move the last entry to the index where the entry to delete is\n            map._entries[toDeleteIndex] = lastEntry;\n            // Update the index for the moved entry\n            map._indexes[lastEntry._key] = toDeleteIndex + 1; // All indexes are 1-based\n\n            // Delete the slot where the moved entry was stored\n            map._entries.pop();\n\n            // Delete the index for the deleted slot\n            delete map._indexes[key];\n\n            return true;\n        } else {\n            return false;\n        }\n    }\n\n    /**\n     * @dev Returns true if the key is in the map. O(1).\n     */\n    function _contains(Map storage map, bytes32 key) private view returns (bool) {\n        return map._indexes[key] != 0;\n    }\n\n    /**\n     * @dev Returns the number of key-value pairs in the map. O(1).\n     */\n    function _length(Map storage map) private view returns (uint256) {\n        return map._entries.length;\n    }\n\n   /**\n    * @dev Returns the key-value pair stored at position `index` in the map. O(1).\n    *\n    * Note that there are no guarantees on the ordering of entries inside the\n    * array, and it may change when more entries are added or removed.\n    *\n    * Requirements:\n    *\n    * - `index` must be strictly less than {length}.\n    */\n    function _at(Map storage map, uint256 index) private view returns (bytes32, bytes32) {\n        require(map._entries.length > index, \"EnumerableMap: index out of bounds\");\n\n        MapEntry storage entry = map._entries[index];\n        return (entry._key, entry._value);\n    }\n\n    /**\n     * @dev Tries to returns the value associated with `key`.  O(1).\n     * Does not revert if `key` is not in the map.\n     */\n    function _tryGet(Map storage map, bytes32 key) private view returns (bool, bytes32) {\n        uint256 keyIndex = map._indexes[key];\n        if (keyIndex == 0) return (false, 0); // Equivalent to contains(map, key)\n        return (true, map._entries[keyIndex - 1]._value); // All indexes are 1-based\n    }\n\n    /**\n     * @dev Returns the value associated with `key`.  O(1).\n     *\n     * Requirements:\n     *\n     * - `key` must be in the map.\n     */\n    function _get(Map storage map, bytes32 key) private view returns (bytes32) {\n        uint256 keyIndex = map._indexes[key];\n        require(keyIndex != 0, \"EnumerableMap: nonexistent key\"); // Equivalent to contains(map, key)\n        return map._entries[keyIndex - 1]._value; // All indexes are 1-based\n    }\n\n    /**\n     * @dev Same as {_get}, with a custom error message when `key` is not in the map.\n     *\n     * CAUTION: This function is deprecated because it requires allocating memory for the error\n     * message unnecessarily. For custom revert reasons use {_tryGet}.\n     */\n    function _get(Map storage map, bytes32 key, string memory errorMessage) private view returns (bytes32) {\n        uint256 keyIndex = map._indexes[key];\n        require(keyIndex != 0, errorMessage); // Equivalent to contains(map, key)\n        return map._entries[keyIndex - 1]._value; // All indexes are 1-based\n    }\n\n    // UintToAddressMap\n\n    struct UintToAddressMap {\n        Map _inner;\n    }\n\n    /**\n     * @dev Adds a key-value pair to a map, or updates the value for an existing\n     * key. O(1).\n     *\n     * Returns true if the key was added to the map, that is if it was not\n     * already present.\n     */\n    function set(UintToAddressMap storage map, uint256 key, address value) internal returns (bool) {\n        return _set(map._inner, bytes32(key), bytes32(uint256(uint160(value))));\n    }\n\n    /**\n     * @dev Removes a value from a set. O(1).\n     *\n     * Returns true if the key was removed from the map, that is if it was present.\n     */\n    function remove(UintToAddressMap storage map, uint256 key) internal returns (bool) {\n        return _remove(map._inner, bytes32(key));\n    }\n\n    /**\n     * @dev Returns true if the key is in the map. O(1).\n     */\n    function contains(UintToAddressMap storage map, uint256 key) internal view returns (bool) {\n        return _contains(map._inner, bytes32(key));\n    }\n\n    /**\n     * @dev Returns the number of elements in the map. O(1).\n     */\n    function length(UintToAddressMap storage map) internal view returns (uint256) {\n        return _length(map._inner);\n    }\n\n   /**\n    * @dev Returns the element stored at position `index` in the set. O(1).\n    * Note that there are no guarantees on the ordering of values inside the\n    * array, and it may change when more values are added or removed.\n    *\n    * Requirements:\n    *\n    * - `index` must be strictly less than {length}.\n    */\n    function at(UintToAddressMap storage map, uint256 index) internal view returns (uint256, address) {\n        (bytes32 key, bytes32 value) = _at(map._inner, index);\n        return (uint256(key), address(uint160(uint256(value))));\n    }\n\n    /**\n     * @dev Tries to returns the value associated with `key`.  O(1).\n     * Does not revert if `key` is not in the map.\n     *\n     * _Available since v3.4._\n     */\n    function tryGet(UintToAddressMap storage map, uint256 key) internal view returns (bool, address) {\n        (bool success, bytes32 value) = _tryGet(map._inner, bytes32(key));\n        return (success, address(uint160(uint256(value))));\n    }\n\n    /**\n     * @dev Returns the value associated with `key`.  O(1).\n     *\n     * Requirements:\n     *\n     * - `key` must be in the map.\n     */\n    function get(UintToAddressMap storage map, uint256 key) internal view returns (address) {\n        return address(uint160(uint256(_get(map._inner, bytes32(key)))));\n    }\n\n    /**\n     * @dev Same as {get}, with a custom error message when `key` is not in the map.\n     *\n     * CAUTION: This function is deprecated because it requires allocating memory for the error\n     * message unnecessarily. For custom revert reasons use {tryGet}.\n     */\n    function get(UintToAddressMap storage map, uint256 key, string memory errorMessage) internal view returns (address) {\n        return address(uint160(uint256(_get(map._inner, bytes32(key), errorMessage))));\n    }\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/utils/StringsUpgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\n/**\n * @dev String operations.\n */\nlibrary StringsUpgradeable {\n    /**\n     * @dev Converts a `uint256` to its ASCII `string` representation.\n     */\n    function toString(uint256 value) internal pure returns (string memory) {\n        // Inspired by OraclizeAPI's implementation - MIT licence\n        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol\n\n        if (value == 0) {\n            return \"0\";\n        }\n        uint256 temp = value;\n        uint256 digits;\n        while (temp != 0) {\n            digits++;\n            temp /= 10;\n        }\n        bytes memory buffer = new bytes(digits);\n        uint256 index = digits - 1;\n        temp = value;\n        while (temp != 0) {\n            buffer[index--] = bytes1(uint8(48 + temp % 10));\n            temp /= 10;\n        }\n        return string(buffer);\n    }\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/proxy/Initializable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\n// solhint-disable-next-line compiler-version\npragma solidity >=0.4.24 <0.8.0;\n\nimport \"../utils/AddressUpgradeable.sol\";\n\n/**\n * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed\n * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an\n * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer\n * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.\n *\n * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as\n * possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.\n *\n * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure\n * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.\n */\nabstract contract Initializable {\n\n    /**\n     * @dev Indicates that the contract has been initialized.\n     */\n    bool private _initialized;\n\n    /**\n     * @dev Indicates that the contract is in the process of being initialized.\n     */\n    bool private _initializing;\n\n    /**\n     * @dev Modifier to protect an initializer function from being invoked twice.\n     */\n    modifier initializer() {\n        require(_initializing || _isConstructor() || !_initialized, \"Initializable: contract is already initialized\");\n\n        bool isTopLevelCall = !_initializing;\n        if (isTopLevelCall) {\n            _initializing = true;\n            _initialized = true;\n        }\n\n        _;\n\n        if (isTopLevelCall) {\n            _initializing = false;\n        }\n    }\n\n    /// @dev Returns true if and only if the function is running in the constructor\n    function _isConstructor() private view returns (bool) {\n        return !AddressUpgradeable.isContract(address(this));\n    }\n}\n"
    },
    "@openzeppelin/contracts-upgradeable-0.7.2/introspection/IERC165Upgradeable.sol": {
      "content": "// SPDX-License-Identifier: MIT\n\npragma solidity ^0.7.0;\n\n/**\n * @dev Interface of the ERC165 standard, as defined in the\n * https://eips.ethereum.org/EIPS/eip-165[EIP].\n *\n * Implementers can declare support of contract interfaces, which can then be\n * queried by others ({ERC165Checker}).\n *\n * For an implementation, see {ERC165}.\n */\ninterface IERC165Upgradeable {\n    /**\n     * @dev Returns true if this contract implements the interface defined by\n     * `interfaceId`. See the corresponding\n     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]\n     * to learn more about how these ids are created.\n     *\n     * This function call must use less than 30 000 gas.\n     */\n    function supportsInterface(bytes4 interfaceId) external view returns (bool);\n}\n"
    },
    "contracts/royalty/IERC2981.sol": {
      "content": "// contracts/royalty/IERC2981.sol\n// SPDX-License-Identifier: MIT\npragma solidity 0.7.3;\n\n/// @dev Interface for the NFT Royalty Standard\ninterface IERC2981 {\n    /// ERC165 bytes to add to interface array - set in parent contract\n    /// implementing this standard\n    ///\n    /// bytes4(keccak256(\"royaltyInfo(uint256,uint256)\")) == 0x2a55205a\n    /// bytes4 private constant _INTERFACE_ID_ERC2981 = 0x2a55205a;\n    /// _registerInterface(_INTERFACE_ID_ERC2981);\n\n    /// @notice Called with the sale price to determine how much royalty\n    //          is owed and to whom.\n    /// @param _tokenId - the NFT asset queried for royalty information\n    /// @param _salePrice - the sale price of the NFT asset specified by _tokenId\n    /// @return receiver - address of who should be sent the royalty payment\n    /// @return royaltyAmount - the royalty payment amount for _salePrice\n    function royaltyInfo(uint256 _tokenId, uint256 _salePrice)\n        external\n        view\n        returns (address receiver, uint256 royaltyAmount);\n}\n"
    }
  },
  "settings": {
    "optimizer": {
      "enabled": true,
      "runs": 999
    },
    "outputSelection": {
      "*": {
        "*": [
          "evm.bytecode",
          "evm.deployedBytecode",
          "devdoc",
          "userdoc",
          "metadata",
          "abi"
        ]
      }
    },
    "libraries": {}
  }
}