def get_effective_agent_id(self):
if self.has_effective_agent():<EOL><INDENT>return self._effective_agent_id<EOL><DEDENT>else:<EOL><INDENT>raise IllegalState()<EOL><DEDENT>
Gets the effective ``Agent Id`` for this proxy.

        :return: the effective agent ``Id``
        :rtype: ``osid.id.Id``
        :raise: ``IllegalState`` -- ``has_effective_agent()`` is ``false``

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