def freeze(self) -> cirq.FrozenCircuit:
        """Creates a FrozenCircuit from this circuit.

        If 'self' is a FrozenCircuit, the original object is returned.
        """
Creates a FrozenCircuit from this circuit.

        If 'self' is a FrozenCircuit, the original object is returned.
        
cirq-core/cirq/circuits/circuit.py