@abc.abstractmethod<EOL><INDENT>def get_agency_form_for_update(self, agency_id):<DEDENT>
return<EOL>
Gets the agency form for updating an existing agency.

        A new agency form should be requested for each update
        transaction.

        :param agency_id: the ``Id`` of the ``Agency``
        :type agency_id: ``osid.id.Id``
        :return: the agency form
        :rtype: ``osid.authentication.AgencyForm``
        :raise: ``NotFound`` -- ``agency_id`` is not found
        :raise: ``NullArgument`` -- ``agency_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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