comefrom: <doocs>1426.Counting Elements_1.py
code: def countElements( arr: List[int]) -> int:
      s = set(arr)
      return sum(x + 1 in s for x in arr)
masked: def sample_funcname ( var_0 : List [ int ] ) -> int :
      var_4 = set ( var_0 )
      return sum ( var_6 + 1 in var_4 for var_6 in var_0 )
  