AssertionError: app.use() requires a generator function
npm install koa-views ，install koa-views version is 5.1.2

use with koa 1.x 

assert.js:89
  throw new assert.AssertionError({
  ^
AssertionError: app.use() requires a generator function
    at Application.app.use (/Users/liwenwu/projects/yuanshuo_koa/node_modules/koa/lib/application.js:106:5)
    at Object.<anonymous> (/Users/liwenwu/projects/yuanshuo_koa/app.js:34:5)
    at Module._compile (module.js:409:26)
    at Object.Module._extensions..js (module.js:416:10)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Function.Module.runMain (module.js:441:10)
    at startup (node.js:134:18)
    at node.js:962:3

when npm install koa-views@4.x 

it's ok
