code: def data_key(data) :
      "returns a unique value that allows data to be used as a dict/set key."
      if isinstance(data, (bytes, float, frozenset, int, str, tuple)) :
          result = data
      else :
          # data itself is non-hashable
          result = id(data)
      #end if
      return \
          resulf data_key(data) :
      "returns a unique value that allows data to be used as a dict/set key."
      if isinstance(data, (bytes, float, frozenset, int, str, tuple)) :
          result = data
      else :
          # data itself is non-hashable
          result = id(data)
      #end if
      return \
          result
docs: returns a unique value that allows data to be used as a dict/set key.