// Well-formed inputs.
    checkFromStringCase("google.com", 80, "google.com", 80, false);
    checkFromStringCase("google.com", 80, "google.com", 80, false);
    checkFromStringCase("192.0.2.1", 82, "192.0.2.1", 82, false);
    checkFromStringCase("[2001::1]", 84, "2001::1", 84, false);
    checkFromStringCase("2001::3", 86, "2001::3", 86, false);
    checkFromStringCase("host:", 80, "host", 80, false);
  }

Then, the browser will send an HTTP `OPTIONS` request to the `:80`-backend, and if the backend sends the appropriate headers authorizing the communication from this different origin (`http://localhost:8080`) then the `:8080`-browser will let the JavaScript in the frontend send its request to the `:80`-backend.

To achieve this, the `:80`-backend must have a list of "allowed origins".

    assertUnescaped(e, '*');

    assertEscaping(e, "%00", '\u0000'); // nul
    assertEscaping(e, "%7F", '\u007f'); // del
    assertEscaping(e, "%C2%80", '\u0080'); // xx-00010,x-000000
    assertEscaping(e, "%DF%BF", '\u07ff'); // xx-11111,x-111111
    assertEscaping(e, "%E0%A0%80", '\u0800'); // xxx-0000,x-100000,x-00,0000
    assertEscaping(e, "%EF%BF%BF", '\uffff'); // xxx-1111,x-111111,x-11,1111

    // Testing multibyte escape sequences
    assertEscaping(e, "%00", '\u0000'); // nul
    assertEscaping(e, "%7F", '\u007f'); // del
    assertEscaping(e, "%C2%80", '\u0080'); // xx-00010,x-000000
    assertEscaping(e, "%DF%BF", '\u07ff'); // xx-11111,x-111111
    assertEscaping(e, "%E0%A0%80", '\u0800'); // xxx-0000,x-100000,x-00,0000
    assertEscaping(e, "%EF%BF%BF", '\uffff'); // xxx-1111,x-111111,x-11,1111

    assertUnescaped(e, '*');

    assertEscaping(e, "%00", '\u0000'); // nul
    assertEscaping(e, "%7F", '\u007f'); // del
    assertEscaping(e, "%C2%80", '\u0080'); // xx-00010,x-000000
    assertEscaping(e, "%DF%BF", '\u07ff'); // xx-11111,x-111111
    assertEscaping(e, "%E0%A0%80", '\u0800'); // xxx-0000,x-100000,x-00,0000
    assertEscaping(e, "%EF%BF%BF", '\uffff'); // xxx-1111,x-111111,x-11,1111

<div class="termy">

```console
$ uvicorn main:app --host 0.0.0.0 --port 80

<span style="color: green;">INFO</span>:     Uvicorn running on http://0.0.0.0:80 (Press CTRL+C to quit)
```

</div>

/// note | "Nota"

O comando `uvicorn main:app` refere-se a:

    // Testing multibyte escape sequences
    assertEscaping(e, "%00", '\u0000'); // nul
    assertEscaping(e, "%7F", '\u007f'); // del
    assertEscaping(e, "%C2%80", '\u0080'); // xx-00010,x-000000
    assertEscaping(e, "%DF%BF", '\u07ff'); // xx-11111,x-111111
    assertEscaping(e, "%E0%A0%80", '\u0800'); // xxx-0000,x-100000,x-00,0000
    assertEscaping(e, "%EF%BF%BF", '\uffff'); // xxx-1111,x-111111,x-11,1111

<div class="termy">

```console
$ uvicorn main:app --host 0.0.0.0 --port 80

<span style="color: green;">INFO</span>:     Uvicorn running on http://0.0.0.0:80 (Press CTRL+C to quit)
```

</div>

/// note

The command `uvicorn main:app` refers to:

RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt

COPY ./app /code/app

CMD ["fastapi", "run", "app/main.py", "--port", "80"]

# If running behind a proxy like Nginx or Traefik add --proxy-headers
# CMD ["fastapi", "run", "app/main.py", "--port", "80", "--proxy-headers"]
```

</details>

## What is a Container

github.com/peterbourgon/diskv v2.0.1+incompatible/go.mod h1:uqqh8zWWbv1HBMNONnaR/tNboyR3/BZd58JJSHlUSCU=
github.com/pires/go-proxyproto v0.8.0 h1:5unRmEAPbHXHuLjDg01CxJWf91cw3lKHc/0xzKpXEe0=
github.com/pires/go-proxyproto v0.8.0/go.mod h1:iknsfgnH8EkjrMeMyvfKByp9TiBZCKZM0jx2xmKqnVY=
github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=