private static final Iterable<@Nullable Integer> ITERABLE_FOUR_NULLS =
      Arrays.asList((Integer) null, null, null, null);

  @SuppressWarnings("JoinIterableIterator") // explicitly testing iterator overload, too
  public void testNoSpecialNullBehavior() {
    checkNoOutput(J, ITERABLE_);
    checkResult(J, ITERABLE_1, "1");
    checkResult(J, ITERABLE_12, "1-2");
    checkResult(J, ITERABLE_123, "1-2-3");

       * crashes on Android when running in 32-bit mode. For maximum safety, we shouldn't use
       * Unsafe.getLong() at all, but the performance benefit on x86_64 is too great to ignore, so
       * as a compromise, we enable the optimization only on platforms that we specifically know to
       * work.
       *

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: Union[bool, None] = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):

`FastAPI` is a class that inherits directly from `Starlette`.

You can use all the <a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a> functionality with `FastAPI` too.

///

### Step 2: create a `FastAPI` "instance"

{* ../../docs_src/first_steps/tutorial001.py hl[3] *}

Here the `app` variable will be an "instance" of the class `FastAPI`.

   * [Call.request] is a redirect to a different address.
   *
   * Prior to OkHttp 4.3 this was incorrectly invoked when the client was ready to read headers.
   * This was misleading for tracing because it was too early.
   */
  open fun responseHeadersStart(call: Call) {
  }

  /**
   * Invoked immediately after receiving response headers.
   *
   * This method is always invoked after [responseHeadersStart].

                + expected
                + ", actual = "
                + actual);
      }
    }

    if (expectedIter.hasNext() || actualIter.hasNext()) {
      // actual either had too few or too many elements
      fail(
          "contents were not equal and in the same order: "
              + "expected = "
              + expected
              + ", actual = "
              + actual);
    }

   * instance. This method is guaranteed to only be called once.
   *
   * <p>By default this returns a new {@link ScheduledExecutorService} with a single thread pool
   * that sets the name of the thread to the {@linkplain #serviceName() service name}. Also, the
   * pool will be {@linkplain ScheduledExecutorService#shutdown() shut down} when the service
   * {@linkplain Service.State#TERMINATED terminates} or {@linkplain Service.State#TERMINATED

    /*
     * This test will catch problems where the underlying iterator
     * throws a RuntimeException when retrieving the nth element.
     *
     * If the PeekingIterator is caching elements too aggressively,
     * it may throw the exception on the (n-1)th element (oops!).
     */

    /* Checks the case where the first element throws an exception. */

    List<Integer> list = emptyList();

در آخرین نظرسنجی توسعه دهندگان پایتون کاملا مشخص بود که <a href="https://www.jetbrains.com/research/python-developers-survey-2017/#tools-and-features" class="external-link" target="_blank">بیشترین ویژگی مورد استفاده از "<abbr title="autocompletion">تکمیل خودکار</abbr>" است</a>.

## Pydantic

모든 데이터 검증은 <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a>에 의해 내부적으로 수행되므로 이로 인한 이점을 모두 얻을 수 있습니다. 여러분은 관리를 잘 받고 있음을 느낄 수 있습니다.

`str`, `float`, `bool`, 그리고 다른 여러 복잡한 데이터 타입 선언을 할 수 있습니다.

이 중 몇 가지는 자습서의 다음 장에 설명되어 있습니다.

## 순서 문제

*경로 작동*을 만들때 고정 경로를 갖고 있는 상황들을 맞닥뜨릴 수 있습니다.

`/users/me`처럼, 현재 사용자의 데이터를 가져온다고 합시다.