def _NormalizeDuration(self, seconds, nanos):
    """Set Duration by seconds and nanos."""
    # Force nanos to be negative if the duration is negative.
    if seconds < 0 and nanos > 0:
      seconds += 1
      nanos -= _NANOS_PER_SECOND
    self.seconds = seconds
    self.nanos = nanos
Set Duration by seconds and nanos.
deps/protobuf/python/google/protobuf/internal/well_known_types.py