app.get('/users', (req, res) => {
  res.send('GET request');
});
app.post('/users', (req, res) => {
  res.send('POST request');
});
app.put('/users/:id', (req, res) => {
  res.send('PUT request');
});
app.delete('/users/:id', (req, res) => {
  res.send('DELETE request');
});