def __init__(self, p: float) -> None:
        """Construct a channel that probabilistically flips the sign of the phase.
        Args:
            p: the probability of a phase flip.

        Raises:
            ValueError: if p is not a valid probability.
        """
        self._p = value.validate_probability(p, 'p')
        self._delegate = AsymmetricDepolarizingChannel(0.0, 0.0, p)
Construct a channel that probabilistically flips the sign of the phase.
        Args:
            p: the probability of a phase flip.

        Raises:
            ValueError: if p is not a valid probability.
        
cirq-core/cirq/ops/common_channels.py