@abc.abstractmethod<EOL><INDENT>def expand_recurring_events(self, recurring_event_ids):<DEDENT>
return<EOL>
Expands the given recurring events into a series of non- recurring events.

        In plenary mode, the returned list contains all of the events in
        the series, including duplicates, or an error results. In
        comparative mode, events may be omitted from the list and may
        present the elements in any order, including providing a unique
        set.

        :param recurring_event_ids: the list of ``Ids`` to expand
        :type recurring_event_ids: ``osid.id.IdList``
        :return: the returned ``Event list``
        :rtype: ``osid.calendaring.EventList``
        :raise: ``NotFound`` -- an ``Id was`` not found
        :raise: ``NullArgument`` -- ``recurring_event_ids`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

        *compliance: mandatory -- This method must be implemented.*