const Router = require('koa-router')
 const router = new Router()
 router.get('/', async ( ctx )=>{ //lots of codes})
 router.get('/help', async ( ctx )=>{ //lots of codes})
 router.get('/signup', async ( ctx )=>{ //lots of codes})
 router.get('/signin', async ( ctx )=>{ //lots of codes})
 //and more codes