code: function (value) {
              var promise = this.promise, pendings;
              if ((pendings = promise[PROMISE_PENDINGS]) === false) {
                  return null;
              }    // set current promise 's resolved value
                   // maybe a promise or instant value
              // set current promise 's resolved value
              // maybe a promise or instant value
              promise[PROMISE_VALUE] = value;
              pendings = pendings ? [].concat(pendings) : [];
              promise[PROMISE_PENDINGS] = false;
              promise[PROMISE_PROGRESS_LISTENERS] = false;
              util.each(pendings, function (p) {
                  promiseWhen(promise, p[0], p[1]);
              });
              return value;
          }
docs: fulfill defer object's promise
  note: can only be called once
  @param value defer object's value
  @return {KISSY.Promise} defer object's promise