p.registerExtension(a, tok.String(), prefix)
			p.expectOperandEnd()
			return
		} else if r1, r2, scale, ok := p.register(tok.String(), prefix); ok {
			if scale != 0 {
				p.errorf("expected simple register reference")
			}
			a.Type = obj.TYPE_REG
			a.Reg = r1
			if r2 != 0 {
				// Form is R1:R2. It is on RHS and the second register
				// needs to go into the LHS.

!!! note
    If you are a Python expert, and you already know everything about type hints, skip to the next chapter.

## Motivation

Let's start with a simple example:

```Python
{!../../../docs_src/python_types/tutorial001.py!}
```

Calling this program outputs:

```
John Doe
```

The function does the following:

 * it delegates to other components that potentially encounter problems. Then, the problem reporter can focus on
 * providing a simple error message, leaving the donkey work of creating a nice model problem to this component.
 *
 */
class DefaultModelProblemCollector implements ModelProblemCollector {

    private final ModelBuilderResult result;

![Swagger UI](https://fastapi.tiangolo.com/img/index/index-01-swagger-ui-simple.png)

### Documentação Alternativa de APIs

E agora, vá para <a href="http://127.0.0.1:8000/redoc" class="external-link" target="_blank">http://127.0.0.1:8000/redoc</a>.

import org.eclipse.aether.impl.scope.InternalScopeManager;
import org.eclipse.aether.internal.impl.scope.ManagedDependencyContextRefiner;
import org.eclipse.aether.internal.impl.scope.ManagedScopeDeriver;
import org.eclipse.aether.internal.impl.scope.ManagedScopeSelector;
import org.eclipse.aether.internal.impl.scope.OptionalDependencySelector;
import org.eclipse.aether.internal.impl.scope.ScopeDependencySelector;

     * @param allowStubModel A flag controlling the case of a missing POM artifact. If {@code true} and the specified
     *            POM artifact does not exist, a simple stub model will be returned. If {@code false}, an exception will
     *            be thrown.
     * @param request The project building request that holds further parameters, must not be {@code null}.

		t.Fatal(err)
	}
	if _, err = writer.Write([]byte(contents)); err != nil {
		t.Fatal(err)
	}
	if err := writer.Close(); err != nil {
		t.Fatal(err)
	}
	// Simple test to make sure PAX extensions are in effect
	if !bytes.Contains(buf.Bytes(), []byte("PaxHeaders.0")) {
		t.Fatal("Expected at least one PAX header to be written.")
	}

Le tout conçu en composant réutilisable facilement intégrable à vos systèmes, data stores, base de données relationnelle ou NoSQL, etc.

### Injection de dépendances

FastAPI contient un système simple mais extrêmement puissant d'<abbr title='aussi connus sous le nom de "composants", "ressources", "services", "providers"'><strong>Injection de Dépendances</strong></abbr>.

![Swagger UI](https://fastapi.tiangolo.com/img/index/index-01-swagger-ui-simple.png)

### 🎛 🛠️ 🩺

&amp; 🔜, 🚶 <a href="http://127.0.0.1:8000/redoc" class="external-link" target="_blank">http://127.0.0.1:8000/redoc</a>.

👆 🔜 👀 🎛 🏧 🧾 (🚚 <a href="https://github.com/Rebilly/ReDoc" class="external-link" target="_blank">📄</a>):

![ReDoc](https://fastapi.tiangolo.com/img/index/index-02-redoc-simple.png)

### 🗄

## Dependencies

We see that we are going to need some dependencies used in several places of the application.

So we put them in their own `dependencies` module (`app/dependencies.py`).

We will now use a simple dependency to read a custom `X-Token` header:

=== "Python 3.9+"

    ```Python hl_lines="3  6-8" title="app/dependencies.py"
    {!> ../../../docs_src/bigger_applications/app_an_py39/dependencies.py!}
    ```