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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 modify_job(self, id, jobstore=None, **changes):
 """ Modify the properties of a single job. Modifications are passed to this method as extra keyword arguments. :param str id: the identifier of the job :param str jobstore: alias of the job store that contains the job """


        fix_job_def(changes)

        if 'trigger' in changes:
            trigger, trigger_args = pop_trigger(changes)
            self._scheduler.reschedule_job(id, jobstore, trigger, **trigger_args)

        return self._scheduler.modify_job(id, jobstore, **changes)