text: const compose = require('koa-compose');
  
  const logger = (ctx, next) => {
    console.log(`${Date.now()} ${ctx.request.method} ${ctx.request.url}`);
    next();
  };
  
  const main = ctx => {
    ctx.response.body = 'Hello Koa2';
  };
  
  const middlewares = compose([logger, main]);
  app.use(middlewares);
  