docs: def create(cls, duration: Union['Duration', timedelta]) -> 'Duration':
          """Creates a Duration from datetime.timedelta if necessary"""
          if isinstance(duration, cls):
              return duration
          elif isinstance(duration, timedelta):
              duration_in_picos = duration.total_seconds() * 10**12
              return cls(picos=duration_in_picos)
          else:
              raise TypeError(
                  'Only datetime.timedelta and cirq.Duration are supported.')