@abc.abstractmethod<EOL><INDENT>def get_effective_agent(self):<DEDENT>
return<EOL>
Gets the effective ``Agent`` for this proxy.

        :return: the effective agent
        :rtype: ``osid.authentication.Agent``
        :raise: ``IllegalState`` -- ``has_effective_agent()`` is ``false``
        :raise: ``OperationFailed`` -- unable to complete request

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