def get_agent_agency_assignment_session(self):
raise Unimplemented()<EOL>
Gets the session for assigning agent to agency mappings.

        return: (osid.authentication.AgentAgencyAssignmentSession) - a
                ``AgentAgencyAsignmentSession``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_agent_agency_assignment()``
                is ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_agent_agency_assignment()`` is ``true``.*