@abc.abstractmethod<EOL><INDENT>def get_agencies_by_query(self, agency_query):<DEDENT>
return<EOL>
Gets a list of ``Agency`` objects matching the given agency query.

        :param agency_query: the agency query
        :type agency_query: ``osid.authentication.AgencyQuery``
        :return: the returned ``AgencyList``
        :rtype: ``osid.authentication.AgencyList``
        :raise: ``NullArgument`` -- ``agency_query`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure
        :raise: ``Unsupported`` -- ``agency_query`` is not of this service

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