text: const express = require('express');
  const app = express();
  
  const courses = [
      {id: 1, name: 'course1'},
      {id: 2, name: 'course2'},
      {id: 3, name: 'course3'}
  ]
  
  app.get('/', (req, res) => {
      res.send('Hello World');
  });
  
  app.get('/api/courses', (req, res) => {
      res.send([1,2,3]);
  })
  
  app.get('/api/courses/:id', (req, res) => {
      let course = courses.find(c => c.id === parseInt(req.params.id));
      if (!course) res.status(404).send('Course not found');
      res.send(course)
      // res.send(req.query)
  })
  
  const port = process.env.PORT || 3000
  app.listen(3000, () => console.log(`Listening on port ${port}`))