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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def contains(self, expected):
 """ 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. """


        return self._encode_invoke(atomic_reference_contains_codec,
                                   expected=self._to_data(expected))