code: def step_size(self, t0=None, t1=None):
      '''
      Return the time in seconds of a step. If a begin and end timestamp,
      return the time in seconds between them after adjusting for what buckets
      they alias to. If t1 and t0 resolve to the same bucket,
      '''
      if t0!=None and t1!=None:
        tb0 = self.to_bucket( t0 )
        tb1 = self.to_bucket( t1, steps=1 ) # NOTE: "end" of second bucket
        if tb0==tb1:
          return self._step
        return self.from_bucket( tb1 ) - self.from_bucket( tb0 )
      return self._stef step_size(self, t0=None, t1=None):
      '''
      Return the time in seconds of a step. If a begin and end timestamp,
      return the time in seconds between them after adjusting for what buckets
      they alias to. If t1 and t0 resolve to the same bucket,
      '''
      if t0!=None and t1!=None:
        tb0 = self.to_bucket( t0 )
        tb1 = self.to_bucket( t1, steps=1 ) # NOTE: "end" of second bucket
        if tb0==tb1:
          return self._step
        return self.from_bucket( tb1 ) - self.from_bucket( tb0 )
      return self._step
docs: Return the time in seconds of a step. If a begin and end timestamp,
      return the time in seconds between them after adjusting for what buckets
      they alias to. If t1 and t0 resolve to the same bucket,