def __init__(self, *, picos: float = 0, nanos: float = 0) -> None:  # Forces keyword args.
        """Initializes a Timestamp with a time specified in ns and/or ps.

        The time is relative to some unspecified "time zero". If both picos and
        nanos are specified, their contributions away from zero are added.

        Args:
            picos: How many picoseconds away from time zero?
            nanos: How many nanoseconds away from time zero?
        """

        if picos and nanos:
            self._picos = picos + nanos * 1000
        else:
            # Try to preserve type information.
            self._picos = nanos * 1000 if nanos else picos
Initializes a Timestamp with a time specified in ns and/or ps.

        The time is relative to some unspecified "time zero". If both picos and
        nanos are specified, their contributions away from zero are added.

        Args:
            picos: How many picoseconds away from time zero?
            nanos: How many nanoseconds away from time zero?
        
cirq-core/cirq/value/timestamp.py