<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def store(self, domain_event_or_events):
 """ Appends given domain event, or list of domain events, to their sequence. :param domain_event_or_events: domain event, or list of domain events """


        # Convert to sequenced item.
        sequenced_item_or_items = self.item_from_event(domain_event_or_events)

        # Append to the sequenced item(s) to the sequence.
        try:
            self.record_manager.record_sequenced_items(sequenced_item_or_items)
        except RecordConflictError as e:
            raise ConcurrencyError(e)