docs: def _loads(self, string):
          """ If :prop:serialized is True, @string will be unserialized
              using :prop:serializer
          """
          if not self.serialized:
              return self._decode(string)
          if string is not None:
              try:
                  return self.serializer.loads(string)
              except TypeError:
                  #: catches bytes errors with the builtin json library
                  return self.serializer.loads(self._decode(string))
              except pickle.UnpicklingError as e:
                  #: incr and decr methods create issues when pickle serialized
                  #  It's a terrible idea for a serialized instance
                  #  to be performing incr and decr methods, but I think
                  #  it makes sense to catch the error regardless
                  decoded = self._decode(string)
                  if decoded.isdigit():
                      return decoded
                  raise pickle.UnpicklingError(e)