@abc.abstractmethod<EOL><INDENT>def get_agent_form_for_update(self, agent_id):<DEDENT>
return<EOL>
Gets the agent form for updating an existing agent.

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

        :param agent_id: the ``Id`` of the ``Agent``
        :type agent_id: ``osid.id.Id``
        :return: the agent form
        :rtype: ``osid.authentication.AgentForm``
        :raise: ``NotFound`` -- ``agent_id`` is not found
        :raise: ``NullArgument`` -- ``agent_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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