code: def _onOffset(self, dt, businesshours):
          
          # if self.normalize and not _is_normalized(dt):
          #     return False
          # Valid BH can be on the different BusinessDay during midnight
          # Distinguish by the time spent from previous opening time
          if self.n >= 0:
              op = self._prev_opening_time(dt)
          else:
              op = self._next_opening_time(dt)
          span = (dt - op).total_seconds()
          if span <= businesshours:
              return True
          else:
              return False
docs: Slight speedups using calculated values.