docs: function() {
          var failedChanges = _.first(this._opSetQueue);
          this._opSetQueue = _.rest(this._opSetQueue);
          var nextChanges = _.first(this._opSetQueue);
          AV._objectEach(failedChanges, function(op, key) {
            var op1 = failedChanges[key];
            var op2 = nextChanges[key];
            if (op1 && op2) {
              nextChanges[key] = op2._mergeWithPrevious(op1);
            } else if (op1) {
              nextChanges[key] = op1;
            }
          });
          this._saving = this._saving - 1;
        }