Store validator set at a given `height`.
           NOTE: If the validator set already exists at that `height` then an
           exception will be raised.

def store_validator_set(self, height, validators):
        """Store validator set at a given `height`.
           NOTE: If the validator set already exists at that `height` then an
           exception will be raised.
        """
        return backend.query.store_validator_set(self.connection, {'height': height,
                                                                   'validators': validators})