Expected "Location" header field

I am at 10-authentication, trying to get past the test that says "POST /login should 303 with good auth details"

```
/**
* If successful, the logged in user should be redirected to `/`.
*/

app.use(function* login(next) {
if (this.request.path !== '/login') return yield* next;
if (this.request.method === 'GET') return this.response.body = form.replace('{{csrf}}', this.csrf);

if (this.request.method === 'POST') {
var body = yield parse.json(this);

if (body.username !== 'username' || body.password !== 'password') {
return this.response.status = 400;
}
if (body._csrf !== this.csrf) {
return this.response.status = 403;
}

if (body.username === 'username' && body.password === 'password' && body._csrf === this.csrf) {
this.response.status = 303;
this.response.set('Location', '/');
}
}
})
```

here is the test result

```
1) Authentication logging in POST /login should 303 with good auth details:
Error: expected "Location" header field
at Test.assert (/Users/christiansakai/Desktop/workshop/node_modules/supertest/lib/test.js:190:35)
at assert (/Users/christiansakai/Desktop/workshop/node_modules/supertest/lib/test.js:132:12)
at /Users/christiansakai/Desktop/workshop/node_modules/supertest/lib/test.js:129:5
at Test.Request.callback (/Users/christiansakai/Desktop/workshop/node_modules/supertest/node_modules/superagent/lib/node/index.js:746:30)
at Test. (/Users/christiansakai/Desktop/workshop/node_modules/supertest/node_modules/superagent/lib/node/index.js:135:10)
at IncomingMessage. (/Users/christiansakai/Desktop/workshop/node_modules/supertest/node_modules/superagent/lib/node/index.js:938:12)
at endReadableNT (_stream_readable.js:893:12)

```

Can you point me in the right direction?

Start in the 10-authentication lesson and inspect the test for POST /login with valid credentials, then compare its expected response with the login middleware shown here. Done means the authentication test receives a 303 response with the expected Location header.

Written by the indexing model from the issue text.