def extract_entangling_error(match_id: noise_utils.OpIdentifier):
            """Gets the entangling error component of depol_errors[match_id]."""
            unitary_err = cirq.unitary(self.fsim_errors[match_id])
            fid = gate_tabulation_math_utils.unitary_entanglement_fidelity(unitary_err, np.eye(4))
            return 1 - fid
Gets the entangling error component of depol_errors[match_id].
cirq-google/cirq_google/devices/google_noise_properties.py