Similarly, you cannot redefine a path operation:

```Python hl_lines="6  11"
{!../../../docs_src/path_params/tutorial003b.py!}
```

The first one will always be used since the path matches first.

## Predefined values

Using the **SNI extension** discussed above, the TLS Termination Proxy would check which of the TLS (HTTPS) certificates available it should use for this connection, using the one that matches the domain expected by the client.

In this case, it would use the certificate for `someapp.example.com`.

<img src="/img/deployment/https/https03.svg">

    And be compatible with all of them at the same time.

Create a utility function to hash a password coming from the user.

And another utility to verify if a received password matches the hash stored.

And another one to authenticate and return a user.

=== "Python 3.10+"

    ```Python hl_lines="7  48  55-56  59-60  69-75"
    {!> ../../../docs_src/security/tutorial004_an_py310.py!}

<img src="/img/tutorial/dependencies/image01.png">

## Simple usage

If you look at it, *path operation functions* are declared to be used whenever a *path* and *operation* matches, and then **FastAPI** takes care of calling the function with the correct parameters, extracting the data from the request.

Actually, all (or most) of the web frameworks work in this same way.

```

Die folgenden Argumente werden unterstützt:

* `allowed_hosts` – Eine Liste von Domain-Namen, die als Hostnamen zulässig sein sollten. Wildcard-Domains wie `*.example.com` werden unterstützt, um Subdomains zu matchen. Um jeden Hostnamen zu erlauben, verwenden Sie entweder `allowed_hosts=["*"]` oder lassen Sie diese Middleware weg.

Wenn ein eingehender Request nicht korrekt validiert wird, wird eine „400“-Response gesendet.

                dependant=self.dependant,
                dependency_overrides_provider=dependency_overrides_provider,
            )
        )

    def matches(self, scope: Scope) -> Tuple[Match, Scope]:
        match, child_scope = super().matches(scope)
        if match != Match.NONE:
            child_scope["route"] = self
        return match, child_scope


class APIRoute(routing.Route):
    def __init__(