comefrom: <doocs>0268.Missing Number_1.py
code: def missingNumber( nums: List[int]) -> int:
      res = len(nums)
      for i, v in enumerate(nums):
          res ^= i ^ v
      return res
masked: def sample_funcname ( var_0 : List [ int ] ) -> int :
      var_4 = len ( var_0 )
      for var_6 , var_7 in enumerate ( var_0 ) :
          var_4 ^= var_6 ^ var_7
      return var_4
  