text: let callBacks = [];
  
  export default {
    onKeyDown: (event: Object) => {
      callBacks.forEach(callBack => {
        callBack(event);
      });
    },
  
    registerCallBack: (callBack): void => {
      callBacks.push(callBack);
    },
  
    deregisterCallBack: (callBack): void => {
      callBacks = callBacks.filter(cb => cb !== callBack);
    },
  };
  