old_contents: import { createAction } from 'redux-actions';
  import T from './ActionTypes';
  import { wrappedSetTimeout } from '../utils/time';
  import { uniqueId } from '../utils/lodash';
  // uniqueId could be used to help indicate to the reducers
  // when a particular optimistic update has finished:
  // the optimistic update and the real update will share
  // the same unique ID, which is information that can
  // help to coordinate a loading animation on the UI
  
  
  export const windowData       = createAction(T.WINDOW_DATA);
  export const subtractLastName = createAction(T.SUBTRACT_LAST_NAME);
  
  
  export const addName = (delay = 300) =>
      dispatch => {
          const requestId = uniqueId();
          dispatch({ type: T.ADD_NAME, meta: requestId });
          return wrappedSetTimeout(
              () => dispatch(addNameDone('World', requestId)),
              delay
          );
      };
  
  
  export const addNameDone = createAction(
      T.ADD_NAME_DONE,
      name => name,
      requestId => requestId
  );
  
new_contents: import { createAction } from 'redux-actions';
  import T from './ActionTypes';
  import { wrappedSetTimeout } from '../utils/time';
  import { uniqueId } from '../utils/lodash';
  // uniqueId could be used to help indicate to the reducers
  // when a particular optimistic update has finished:
  // the optimistic update and the real update will share
  // the same unique ID, which is information that can
  // help to coordinate a loading animation on the UI
  
  
  export const windowData       = createAction(T.WINDOW_DATA);
  export const subtractLastName = createAction(T.SUBTRACT_LAST_NAME);
  
  
  export const addName = (delay = 300) =>
      dispatch => {
          const requestId = uniqueId();
          dispatch({ type: T.ADD_NAME, meta: requestId });
          return wrappedSetTimeout(
              () => dispatch(addNameDone('World', requestId)),
              delay
          );
      };
  
  
  export const addNameDone = createAction(
      T.ADD_NAME_DONE,
      (name, _) => name,
      (_, requestId) => requestId
  );
  
subject: fix bug in function signature of action creator