code: function(ev, callback) {
        var calls;
        if (!ev) {
          this._callbacks = {};
        } else if (calls = this._callbacks) {
          if (!callback) {
            calls[ev] = [];
          } else {
            var list = calls[ev];
            if (!list) return this;
            for (var i = 0, l = list.length; i < l; i++) {
              if (list[i] && callback === list[i][0]) {
                list[i] = null;
                break;
              }
            }
          }
        }
        return this;
      }
docs: Remove one or many callbacks. If `callback` is null, removes all callbacks for the event. If `ev` is null, removes all bound callbacks for all events.