Updated TupleWithMeta class to make it consistent with other Meta classes in order to avoid confusion. Also made provision to call TupleWithMeta with a tuple containing one or more elements. For more details on how request_id will be returned to the caller, please refer to the approved blueprint [1] discussed with the cross-project team. [1] http://specs.openstack.org/openstack/openstack-specs/specs/return-request-id.html Change-Id: I5a79a4ed8cb4dc83ea3b64499df191750462100d Partial-Implements: blueprint return-request-id-to-caller