code: function (callback) {
              return when(this, function (value) {
                  return callback(value, true);
              }, function (reason) {
                  return callback(reason, false);
              });
          }
docs: call callback when this promise object is rejected or resolved
  @param {Function} callback the second parameter is
  true when resolved and false when rejected
  @@return {KISSY.Promise} a new promise object