Using 'koa-static', app.use(serve('public')) throws a “requires a generator function” error msg

var serve = require('koa-static');
var koa = require('koa');
var app = koa();                              
app.use(serve(__dirname + '/public')); 

Error I am getting is

AssertionError: app.use() requires a generator function

Example over here shows to use this way https://www.npmjs.com/package/koa-static

via Sanket Kumar