comefrom: <qiyuangong>538_Convert_BST_to_Greater_Tree_1.py
code: def convertBST( root):
      total = 0
      
      node = root
      stack = []
      while stack or node is not None:
          while node is not None:
              stack.append(node)
              node = node.right
      
          node = stack.pop()
          total += node.val
          node.val = total
      
          node = node.left
      
      return root
masked: def sample_funcname ( var_0 ) :
      var_2 = 0
      var_3 = var_0
      var_4 = [ ]
      while var_4 or var_3 is not None :
          while var_3 is not None :
              var_4.append ( var_3 )
              var_3 = var_3.right
          var_3 = var_4.pop ( )
          var_2 += var_3.val
          var_3.val = var_2
          var_3 = var_3.left
      return var_0
  