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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 NewDefaultServicePeriod(self):
 """Create a new ServicePeriod object, make it the default service period and return it. The default service period is used when you create a trip without providing an explict service period. """

    service_period = self._gtfs_factory.ServicePeriod()
    service_period.service_id = util.FindUniqueId(self.service_periods)
    # blank service won't validate in AddServicePeriodObject
    self.SetDefaultServicePeriod(service_period, validate=False)
    return service_period