function visibilityFilter(state = 'SHOW_ALL', action) {
case 'SET_VISIBILITY_FILTER':
function todos(state = [], action) {
...state.slice(0, action.index),
Object.assign({}, state[action.index], {
...state.slice(action.index + 1)
import { combineReducers, createStore } from 'redux';
let reducer = combineReducers({ visibilityFilter, todos });
let store = createStore(reducer);