rootReducers.js

import { combineReducers } from 'redux'

import nav from './nav'
// #1. remove the contactsReducer, and replace it with profilesReducer instead
import profilesReducer from '../profiles/reducers'

const appReducer = combineReducers({
  nav,
  // #2. register it on combineReducers, note: because we can register many reducer here
  profilesReducer
})

export default appReducer