@abc.abstractmethod<EOL><INDENT>def get_assignable_agency_ids_for_agent(self, agency_id, agent_id):<DEDENT>
return<EOL>
Gets a list of agencies including and under the given agency node in which a specific agent can be assigned.

        :param agency_id: the ``Id`` of the ``Agency``
        :type agency_id: ``osid.id.Id``
        :param agent_id: the ``Id`` of the ``Agent``
        :type agent_id: ``osid.id.Id``
        :return: list of assignable bin ``Ids``
        :rtype: ``osid.id.IdList``
        :raise: ``NullArgument`` -- ``agency_id`` or ``agent_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request

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