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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _onOffset(self, dt, businesshours):
 """ Slight speedups using calculated values. """

        # 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