docs: function resolveRequest({ requestKey, res, err }) {
    const handlers = requests[requestKey] || [];
  
    handlers.forEach(handler => {
      if (res) {
        handler.resolve(res);
      } else {
        handler.reject(err);
      }
    });
  
    // This list of handlers has been, well, handled. So we
    // clear the handlers for the next request.
    requests[requestKey] = null;
  }