*   <li>No stats are modified by operations invoked on the {@linkplain Cache#asMap asMap} view of
 *       the cache.
 * </ul>
 *
 * <p>A lookup is specifically defined as an invocation of one of the methods {@link
 * LoadingCache#get(Object)}, {@link LoadingCache#getUnchecked(Object)}, {@link Cache#get(Object,
 * Callable)}, or {@link LoadingCache#getAll(Iterable)}.
 *
 * @author Charles Fry

   * comes from a data structure supporting efficient indexed random access, typically an array or
   * list.
   *
   * <p>The order of the resulting stream is defined if and only if the order of the original stream
   * was defined.
   */
  public static <T extends @Nullable Object, R extends @Nullable Object> Stream<R> mapWithIndex(
      Stream<T> stream, FunctionWithIndex<? super T, ? extends R> function) {

Você também obterá preenchimento automático para o corpo a ser enviado:

<img src="/img/tutorial/generate-clients/image03.png">

/// tip | Dica

Observe o preenchimento automático para `name` e `price`, que foi definido no aplicativo FastAPI, no modelo `Item`.

///

Você terá erros em linha para os dados que você envia:

<img src="/img/tutorial/generate-clients/image04.png">

But it was created before there existed Python type hints. So, to define every <abbr title="the definition of how data should be formed">schema</abbr> you need to use specific utils and classes provided by Marshmallow.

/// check | Inspired **FastAPI** to

Use code to define "schemas" that provide data types and validation, automatically.

///

As an example, let's take this function:

{* ../../docs_src/python_types/tutorial009c.py hl[1,4] *}

The parameter `name` is defined as `Optional[str]`, but it is **not optional**, you cannot call the function without the parameter:

```Python
say_hi()  # Oh, no, this throws an error! 😱
```

     *
     * The source indicates whether the property is:
     * - Set by Maven itself at startup (SYSTEM_PROPERTIES)
     * - Configured by users through external means like CLI options (USER_PROPERTIES)
     * - Defined in the project's POM file (MODEL)
     *
     * @return the source of the configuration property, defaults to USER_PROPERTIES
     * @see Source for detailed information about each source type and when it's used
     */

    "SelfEquals", // TODO(cpovirk): Consider using EqualsTester from Guava.
    "UndefinedEquals", // Comparisons of an object to itself *are* defined.
  })
  public void testEquals_self() {
    assertTrue("An Object should be equal to itself.", collection.equals(collection));
  }

  // Comparisons to null *are* defined.
  @SuppressWarnings("UndefinedEquals")
  public void testEquals_null() {
    // noinspection ObjectEqualsNull

`xl.meta` is a new self describing backend format used by MinIO to support AWS S3 compatible versioning.
This file is the source of truth for each `version` at rest. `xl.meta` is a msgpack file serialized from a
well defined data structure. To understand `xl.meta` here are the few things to start with

`xl.meta` carries first 8 bytes an XL header which describes the current format and the format version,

 * by other {@code CycleDetectingLockFactory} instances (except those with {@code Policy.DISABLED}).
 * A lock's behavior when a cycle is detected, however, is defined by the {@code Policy} of the
 * factory that created it. This allows detection of cycles across components while delegating
 * control over lock behavior to individual components.
 *

    * This will be used by the **automatic docs**.
    * It will also be used by automatic client code generation tools.

But most importantly:

* It will **limit and filter** the output data to what is defined in the return type.
    * This is particularly important for **security**, we'll see more of that below.

## `response_model` Parameter { #response-model-parameter }