def has_end(self):
        return bool(self._end_time or self._duration)
Optional attribute not present, don't issue note.
dataset/ETHPy150Open C4ptainCrunch/ics.py/ics/event.py/Event.has_end--crossover with--dataset/ETHPy150Open typesupply/woffTools/Lib/woffTools/test/test_validate.py/metadataAbstractElementOptionalAttributesTest3