      *             ]},
      *             function_7
      *         ],
+     *         success: _onSuccessHandler,
      *         error  : _onErrorHandler,
      *         anyway : _onFinallyHandler
      *     });


    /**
     * Flexible asynchronous tasker.
     *
     * Usage:
     * <pre>

     *     [Sequence]:
     *                   |3 ------>|
     *                   |         |
     *         1 -> 2 -> |4 ------>| -> 7 -> success -> anyway
     *                   |         |        (or error)
     *                   |5 -> 6 ->|
     *
     * </pre>
