assertThat(network.edgesConnecting(N1, N1)).isEmpty();
    assertThat(network.edgesConnecting(N1, N2)).containsExactly(E12);
  }

  @Test
  public void concurrentIteration() throws Exception {
    addEdge(1, 2, "foo");
    addEdge(3, 4, "bar");
    addEdge(5, 6, "baz");

    int threadCount = 20;
    ExecutorService executor = newFixedThreadPool(threadCount);
    final CyclicBarrier barrier = new CyclicBarrier(threadCount);

   * ...
   * synchronized (table) {  // Synchronizing on table, not row!
   *   Iterator<Entry<C, V>> i = row.entrySet().iterator(); // Must be in synchronized block
   *   while (i.hasNext()) {
   *     foo(i.next());
   *   }
   * }
   * }</pre>
   *
   * <p>Failure to follow this advice may result in non-deterministic behavior.
   *

    * Nếu không, client sẽ thấy một lỗi rõ ràng và hữu ích.
* Kiểm tra xem nếu có một tham số `q` trong query string (ví dụ như `http://127.0.0.1:8000/items/foo?q=somequery`) cho request `GET`.
    * Tham số `q` được định nghĩa `= None`, nó là tùy chọn.
    * Nếu không phải `None`, nó là bắt buộc (như body trong trường hợp của `PUT`).

---

回到前面的代码示例，**FastAPI** 将会：

* 校验 `GET` 和 `PUT` 请求的路径中是否含有 `item_id`。
* 校验 `GET` 和 `PUT` 请求中的 `item_id` 是否为 `int` 类型。
    * 如果不是，客户端将会收到清晰有用的错误信息。
* 检查 `GET` 请求中是否有命名为 `q` 的可选查询参数（比如 `http://127.0.0.1:8000/items/foo?q=somequery`）。
    * 因为 `q` 被声明为 `= None`，所以它是可选的。
    * 如果没有 `None` 它将会是必需的 (如 `PUT` 例子中的请求体)。
* 对于访问 `/items/{item_id}` 的 `PUT` 请求，将请求体读取为 JSON 并：
    * 检查是否有必需属性 `name` 并且值为 `str` 类型 。

Ve uzun süre kuyrukta beklemek 🕙 zorundasın yoksa sıranı kaybedersin.

Muhtemelen ayak işlerı yaparken sevgilini 😍 bankaya 🏦 getirmezsin.

### Burger Sonucu

Bu "aşkınla fast food burgerleri" senaryosunda, çok fazla bekleme olduğu için 🕙, eşzamanlı bir sisteme sahip olmak çok daha mantıklı ⏸🔀⏯.

Web uygulamalarının çoğu için durum böyledir.

    * Jeżeli nie jest, odbiorca zobaczy przydatną, przejrzystą wiadomość z błędem.
* Sprawdzi czy w ścieżce jest opcjonalny parametr zapytania `q` (np. `http://127.0.0.1:8000/items/foo?q=somequery`) dla żądania `GET`.
    * Jako że parametr `q` jest zadeklarowany jako `= None`, jest on opcjonalny.
    * Gdyby tego `None` nie było, parametr ten byłby wymagany (tak jak treść żądania w żądaniu `PUT`).

  }

  @GwtIncompatible("builder internals")
  public void testReusedBuilder() {
    ImmutableList.Builder<String> builder = new ImmutableList.Builder<String>();
    for (int i = 0; i < 10; i++) {
      builder.add("foo");
    }
    builder.add("bar");
    RegularImmutableList<String> list = (RegularImmutableList<String>) builder.build();
    builder.add("baz");
    assertTrue(list.array != builder.contents);
  }

👟 🔙 ⏮️ 📟 🖼, **FastAPI** 🔜:

* ✔ 👈 📤 `item_id` ➡ `GET` & `PUT` 📨.
* ✔ 👈 `item_id` 🆎 `int` `GET` & `PUT` 📨.
    * 🚥 ⚫️ 🚫, 👩‍💻 🔜 👀 ⚠, 🆑 ❌.
* ✅ 🚥 📤 📦 🔢 🔢 📛 `q` ( `http://127.0.0.1:8000/items/foo?q=somequery`) `GET` 📨.
    *  `q` 🔢 📣 ⏮️ `= None`, ⚫️ 📦.
    * 🍵 `None` ⚫️ 🔜 🚚 (💪 💼 ⏮️ `PUT`).
*  `PUT` 📨 `/items/{item_id}`, ✍ 💪 🎻:
    * ✅ 👈 ⚫️ ✔️ ✔ 🔢 `name` 👈 🔜 `str`.

-   לאמת שה - `item_id` הוא מטיפוס `int` בבקשות `GET` ו - `PUT`.
    -   אם הוא לא, הלקוח יראה שגיאה ברורה ושימושית.
-   לבדוק האם קיים פרמטר שאילתא בשם `q` (קרי `http://127.0.0.1:8000/items/foo?q=somequery`) לבקשות `GET`.
    -   מאחר והפרמטר `q` מוגדר עם <code dir="ltr"> = None</code>, הוא אופציונלי.
    -   לולא ה - `None` הוא היה חובה (כמו הגוף במקרה של `PUT`).

     * LF<? extends @Nullable V>. That might be better: There's currently no difference between the
     * outputs users get when calling this with <Foo> and calling it with <@Nullable Foo>. The only
     * difference is that calling it with <Foo> won't work when an input Future has a @Nullable
     * type. So why even make that error possible by giving callers the choice?
     *