code: function () {
          var pending = this._pending,
              done = this._done,
              a,
              b;
          while (0 !== pending.length) {
              b = pending.pop();
              a = pending.pop();
              done.push(a, b);
              if (this._areDifferent(a, b)) {
                  return false;
              }
          }
          return true;
      }
docs: Process the pending list
  
  @return {Boolean}