code: function(name, callback, context) {
        if (!eventsApi(this, 'once', name, [callback, context]) || !callback) return this;
        var self = this;
        var once = _.once(function() {
          self.off(name, once);
          callback.apply(this, arguments);
        });
        once._callback = callback;
        return this.on(name, once, context);
      }
docs: Bind an event to only be triggered a single time. After the first time the callback is invoked, it will be removed.