code: def contains(self, expected):
          
  
          return self._encode_invoke(atomic_reference_contains_codec,
                                     expected=self._to_data(expected))
docs: Checks if the reference contains the value.
  
          :param expected: (object), the value to check (is allowed to be ``None``).
          :return: (bool), ``true`` if the value is found, ``false`` otherwise.