}

  private static String paramString(Class<?> type, int i) {
    return type.getSimpleName() + '@' + i;
  }

  /**
   * Annotates a method to be the instance generator of a certain type. The return type is the
   * generated type. The method parameters correspond to the generated type's type parameters. For

vous verrez comme réponse :

```JSON
{"item_id":"foo"}
```

## Paramètres de chemin typés

Vous pouvez déclarer le type d'un paramètre de chemin dans la fonction, en utilisant les annotations de type Python :


```Python hl_lines="7"
{!../../docs_src/path_params/tutorial002.py!}
```

Ici, `item_id` est déclaré comme `int`.

/// check | "vérifier"

```

By declaring a *path operation function* parameter with the type being the `Request` **FastAPI** will know to pass the `Request` in that parameter.

/// tip

Note that in this case, we are declaring a path parameter beside the request parameter.

So, the path parameter will be extracted, validated, converted to the specified type and annotated with OpenAPI.

7. Here the `response_model` is using a type annotation of a list of `Author` dataclasses.

    Again, you can combine `dataclasses` with standard type annotations.

8. Notice that this *path operation function* uses regular `def` instead of `async def`.

    As always, in FastAPI you can combine `def` and `async def` as needed.

    return proxyClass.isInstance(arg)
        // Equal proxy instances should mostly be instance of proxyClass
        // Under some edge cases (such as the proxy of JDK types serialized and then deserialized)
        // the proxy type may not be the same.
        // We first check isProxyClass() so that the common case of comparing with non-proxy objects
        // is efficient.
        || (Proxy.isProxyClass(arg.getClass())

        assertArgumentNotNull("type", type);
        assertArgumentNotNull("clazz", clazz);

        if (type instanceof Class) {
            return clazz.isAssignableFrom((Class<?>) type);
        }
        if (type instanceof ParameterizedType) {
            final ParameterizedType parameterizedType = ParameterizedType.class.cast(type);
            return isTypeOf(parameterizedType.getRawType(), clazz);

///

## Use `Annotated` in the type for the `q` parameter

Remember I told you before that `Annotated` can be used to add metadata to your parameters in the [Python Types Intro](../python-types.md#type-hints-with-metadata-annotations){.internal-link target=_blank}?

Now it's the time to use it with FastAPI. 🚀

We had this type annotation:

//// tab | Python 3.10+

```Python

 *     ExecutionException}, {@code UncheckedExecutionException}, and {@code ExecutionError}. Any
 *     code that is still catching {@code ComputationException} may need to be updated to catch some
 *     of those types instead. (Note that this type, though deprecated, is not planned to be removed
 *     from Guava.)
 */
@Deprecated
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class ComputationException extends RuntimeException {

          <name>modelVersion</name>
          <version>1.1.0+</version>
          <type>String</type>
          <description>The version of the underlying metadata model.</description>
        </field>
        <field>
          <name>groupId</name>
          <version>1.0.0+</version>
          <type>String</type>

 *
 * <p>Implementations of this interface are expected to be thread-safe, and can be safely accessed
 * by multiple concurrent threads.
 *
 * @param <K> the type of the cache's keys, which are not permitted to be null
 * @param <V> the type of the cache's values, which are not permitted to be null
 * @author Charles Fry
 * @since 10.0
 */
@DoNotMock("Use CacheBuilder.newBuilder().build()")
@GwtCompatible