def _has_unitary_(self) -> bool:
        """Whether this value has a unitary matrix representation.

        This method is used by the global `cirq.has_unitary` method.  If this
        method is not present, or returns NotImplemented, it will fallback
        to using _unitary_ with a default value, or False if neither exist.

        Returns:
            True if the value has a unitary matrix representation, False
            otherwise.
        """
Whether this value has a unitary matrix representation.

        This method is used by the global `cirq.has_unitary` method.  If this
        method is not present, or returns NotImplemented, it will fallback
        to using _unitary_ with a default value, or False if neither exist.

        Returns:
            True if the value has a unitary matrix representation, False
            otherwise.
        
cirq-core/cirq/protocols/unitary_protocol.py