<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_occurrence(self, occ):
 """ Return a persisted occurrences matching the occ and remove it from lookup since it has already been matched """

        return self.lookup.pop(
            (occ.event, occ.original_start, occ.original_end),
            occ)