Iterator<String> unfiltered = Lists.newArrayList("foo", "bar").iterator();
    Iterator<String> filtered = filter(unfiltered, equalTo("foo"));
    List<String> expected = singletonList("foo");
    List<String> actual = Lists.newArrayList(filtered);
    assertEquals(expected, actual);
  }

  public void testFilterNoMatch() {
    Iterator<String> unfiltered = Lists.newArrayList("foo", "bar").iterator();

HSPLkotlin/coroutines/AbstractCoroutineContextElement;-><init>(Lkotlin/coroutines/CoroutineContext$Key;)V
HSPLkotlin/coroutines/AbstractCoroutineContextElement;->fold(Ljava/lang/Object;Lkotlin/jvm/functions/Function2;)Ljava/lang/Object;
HSPLkotlin/coroutines/AbstractCoroutineContextElement;->getKey()Lkotlin/coroutines/CoroutineContext$Key;

 * returned.
 *
 * <p>All default instances returned by {@link #get} are generics-safe. Clients won't get type
 * errors for using {@code get(Comparator.class)} as a {@code Comparator<Foo>}, for example.
 * Immutable empty instances are returned for collection types; {@code ""} for string; {@code 0} for
 * number types; reasonable default instance for other stateless types. For mutable types, a fresh

   * @since 10.0
   */
  public static String toAddrString(InetAddress ip) {
    checkNotNull(ip);
    if (ip instanceof Inet4Address) {
      // For IPv4, Java's formatting is good enough.
      // requireNonNull accommodates Android's @RecentlyNullable annotation on getHostAddress
      return requireNonNull(ip.getHostAddress());
    }
    byte[] bytes = ip.getAddress();

* `item_id`'nin `GET` ve `PUT` istekleri için, tipinin `int` olduğunu doğrulayacak.
    * Eğer değilse, sebebini belirten bir hata mesajı gösterecek.
* Opsiyonel bir `q` parametresinin `GET` isteği içinde (`http://127.0.0.1:8000/items/foo?q=somequery` gibi) olup olmadığını kontrol edecek
    * `q` parametresini `= None` ile oluşturduğumuz için, opsiyonel bir parametre olacak.
    * Eğer `None` olmasa zorunlu bir parametre olacaktı (`PUT` metodunun gövdesinde olduğu gibi).

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* Validate that the `item_id` is of type `int` for `GET` and `PUT` requests.
    * If it is not, the client will see a useful, clear error.
* Check if there is an optional query parameter named `q` (as in `http://127.0.0.1:8000/items/foo?q=somequery`) for `GET` requests.
    * As the `q` parameter is declared with `= None`, it is optional.
    * Without the `None` it would be required (as is the body in the case with `PUT`).

    * Si ce n'est pas le cas, le client voit une erreur utile et claire.
* Vérifier qu'il existe un paramètre de requête facultatif nommé `q` (comme dans `http://127.0.0.1:8000/items/foo?q=somequery`) pour les requêtes `GET`.
    * Puisque le paramètre `q` est déclaré avec `= None`, il est facultatif.

* Validará que el `item_id` sea del tipo `int` para requests `GET` y `PUT`.
    * Si no lo es, el cliente verá un error útil y claro.
* Comprobará si hay un parámetro de query opcional llamado `q` (como en `http://127.0.0.1:8000/items/foo?q=somequery`) para requests `GET`.
    * Como el parámetro `q` está declarado con `= None`, es opcional.
    * Sin el `None` sería requerido (como lo es el body en el caso con `PUT`).

---

回到前面的的程式碼範例，**FastAPI** 還會：

- 驗證 `GET` 和 `PUT` 請求路徑中是否包含 `item_id`。
- 驗證 `GET` 和 `PUT` 請求中的 `item_id` 是否是 `int` 型別。
    - 如果驗證失敗，將會返回清楚有用的錯誤訊息。
- 查看 `GET` 請求中是否有命名為 `q` 的查詢參數 (例如 `http://127.0.0.1:8000/items/foo?q=somequery`)。
    - 因為 `q` 參數被宣告為 `= None`，所以是選填的。
    - 如果沒有宣告 `None`，則此參數將會是必填 (例如 `PUT` 範例的請求 body)。
- 對於 `PUT` 的請求 `/items/{item_id}`，將會讀取 body 為 JSON：
    - 驗證是否有必填屬性 `name` 且型別是 `str`。