docs: function (keyCode, cb) {
              if (keyCode == this.KEYS.VK_SHIFT) {
                  this._keyShift = true;
              }
              if (keyCode == this.KEYS.VK_CTRL) {
                  this._keyCtrl = true;
              }
              if (typeof keyCode == "string" && this._keyShift) {
                  keyCode = keyCode.toUpperCase();
              }
              if (keyCode == this.KEYS.VK_ALT) {
                  this._keyAlt = true;
              }
              this._sendEvent('keydown', keyCode, null, null, this._getModifier());
              this._callCallback(cb);
          }