@abc.abstractmethod<EOL><INDENT>def get_compositions_by_query(self, composition_query):<DEDENT>
return<EOL>
Gets a list of ``Compositions`` matching the given composition query.

        :param composition_query: the composition query
        :type composition_query: ``osid.repository.CompositionQuery``
        :return: the returned ``CompositionList``
        :rtype: ``osid.repository.CompositionList``
        :raise: ``NullArgument`` -- ``composition_query`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure
        :raise: ``Unsupported`` -- ``composition_query`` is not of this service

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