def from_proto(
        self,
        proto: v2.program_pb2.Tag,
        *,
        constants: list[v2.program_pb2.Constant],
        deserialized_constants: list[Any],
    ) -> Any:
        """Converts a proto-formatted operation into a Cirq operation.

        Args:
            proto: The proto object to be deserialized.
            constants: The list of Constant protos referenced by constant
                table indices in `proto`.
            deserialized_constants: The deserialized contents of `constants`.

        Returns:
            The deserialized operation represented by `proto`.
        """
Converts a proto-formatted operation into a Cirq operation.

        Args:
            proto: The proto object to be deserialized.
            constants: The list of Constant protos referenced by constant
                table indices in `proto`.
            deserialized_constants: The deserialized contents of `constants`.

        Returns:
            The deserialized operation represented by `proto`.
        
cirq-google/cirq_google/serialization/tag_deserializer.py