@abc.abstractmethod<EOL><INDENT>def get_schedules_by_date_range(self, from_, to):<DEDENT>
return<EOL>
Gets a ``ScheduleList`` contained by the given date range inclusive.

        In plenary mode, the returned list contains all known schedule
        or an error results. Otherwise, the returned list may contain
        only those schedule that are accessible through this session.

        :param from: start of date range
        :type from: ``osid.calendaring.DateTime``
        :param to: end of date range
        :type to: ``osid.calendaring.DateTime``
        :return: the returned ``Schedule`` list
        :rtype: ``osid.calendaring.ScheduleList``
        :raise: ``InvalidArgument`` -- ``from`` is greater than ``to``
        :raise: ``NullArgument`` -- ``from`` or ``to`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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