import subprocess

from playwright.sync_api import Playwright, sync_playwright


# Run playwright codegen to generate the code below, copy paste the sections in run()
def run(playwright: Playwright) -> None:
    browser = playwright.chromium.launch(headless=False)
    # Update the viewport manually
    context = browser.new_context(viewport={"width": 960, "height": 1080})
    page = context.new_page()
    page.goto("http://localhost:8000/docs")

import subprocess
import time

import httpx
from playwright.sync_api import Playwright, sync_playwright


# Run playwright codegen to generate the code below, copy paste the sections in run()
def run(playwright: Playwright) -> None:
    browser = playwright.chromium.launch(headless=False)
    # Update the viewport manually
    context = browser.new_context(viewport={"width": 960, "height": 1080})
    page = context.new_page()

```

这表示 `item` 可以是 `int` 或 `str`。

#### 可能为 `None` { #possibly-none }

你可以声明一个值的类型是某种类型（比如 `str`），但它也可能是 `None`。

//// tab | Python 3.10+

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

////

使用 `str | None` 而不是仅仅 `str`，可以让编辑器帮助你发现把值当成总是 `str` 的错误（实际上它也可能是 `None`）。

### 类作为类型 { #classes-as-types }

你也可以把类声明为变量的类型。

import re
import sys
from datetime import date

RELEASE_NOTES_FILE = "docs/en/docs/release-notes.md"
RELEASE_HEADER_PATTERN = re.compile(r"^## (\d+\.\d+\.\d+)\s*(\(.*\))?\s*$")


def main() -> None:
    with open(RELEASE_NOTES_FILE) as f:
        lines = f.readlines()

    for i, line in enumerate(lines):
        match = RELEASE_HEADER_PATTERN.match(line)
        if not match:
            continue

import subprocess
import time

import httpx
from playwright.sync_api import Playwright, sync_playwright


# Run playwright codegen to generate the code below, copy paste the sections in run()
def run(playwright: Playwright) -> None:
    browser = playwright.chromium.launch(headless=False)
    # Update the viewport manually
    context = browser.new_context(viewport={"width": 960, "height": 1080})
    page = context.new_page()

     * @param url the URL that requires authentication
     * @param sae the authentication exception that was thrown
     * @return credentials returned by prompt or null if none available
     */

    public static NtlmPasswordAuthentication requestNtlmPasswordAuthentication(final String url, final SmbAuthException sae) {
        if (auth == null) {
            return null;
        }

from fastapi import FastAPI, Response
from fastapi.responses import RedirectResponse

app = FastAPI()


@app.get("/portal", response_model=None)
async def get_portal(teleport: bool = False) -> Response | dict:
    if teleport:
        return RedirectResponse(url="https://www.youtube.com/watch?v=dQw4w9WgXcQ")

    tests, either. This causes it to fail to find AtomicLongMapTest.

    Our workaround is to tell GWT that util.concurrent and all other packages
    have prod supersource, even if they have none. GWT is happy to ignore us
    when we specify a nonexistent path.

    (I hope that this workaround does not cause its own problems in the future.)
-->
<super-source path="super"/>

from fastapi import FastAPI
from fastapi.testclient import TestClient


def test_no_content():
    app = FastAPI()

    @app.get("/no-content", status_code=http.HTTPStatus.NO_CONTENT)
    def return_no_content() -> "None":
        return

    client = TestClient(app)
    response = client.get("/no-content")
    assert response.status_code == http.HTTPStatus.NO_CONTENT, response.text

import subprocess
import time

import httpx
from playwright.sync_api import Playwright, sync_playwright


# Run playwright codegen to generate the code below, copy paste the sections in run()
def run(playwright: Playwright) -> None:
    browser = playwright.chromium.launch(headless=False)
    # Update the viewport manually
    context = browser.new_context(viewport={"width": 960, "height": 1080})
    browser = playwright.chromium.launch(headless=False)