Youtube in React: channels reducer skeleton

channels.js

import {VIDEO_DETAILS, WATCH_DETAILS} from '../actions/watch';
import {SUCCESS} from '../actions';
import {CHANNEL_LIST_RESPONSE} from '../api/youtube-api-response-types';

const initialState = {
  byId: {}
};

export default function (state = initialState, action) {
  switch (action.type) {
    case WATCH_DETAILS[SUCCESS]:
      return reduceWatchDetails(action.response, state);
    default:
      return state;
  }
}