def _CZ_right(self, q, r):
        r"""Right multiplication version of CZ gate."""
        self.M[:, q] ^= self.F[:, r]
        self.M[:, r] ^= self.F[:, q]
        self.gamma[:] = (self.gamma[:] + 2 * self.F[:, q] * self.F[:, r]) % 4
Right multiplication version of CZ gate.
cirq-core/cirq/sim/clifford/stabilizer_state_ch_form.py