}
            ]
        }
    )


def test_query_optional():
    response = client.get("/query/optional")
    assert response.status_code == 200
    assert response.json() == "foo bar"


def test_query_optional_query_baz():
    response = client.get("/query/optional?query=baz")
    assert response.status_code == 200
    assert response.json() == "foo bar baz"

from typing import Optional

from fastapi import Depends, FastAPI, Security
from fastapi.security.open_id_connect_url import OpenIdConnect
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

oid = OpenIdConnect(openIdConnectUrl="/openid", auto_error=False)


class User(BaseModel):
    username: str


def get_current_user(oauth_header: Optional[str] = Security(oid)):
    if oauth_header is None:

                 TF_Message(first_bad_status.get()));
  }
}

absl::optional<std::vector<std::unique_ptr<ParallelTensor>>>
ParallelDevice::Join(
    const std::vector<PartialTensorShape>& expected_output_shapes,
    TF_Status* status) const {
  absl::optional<std::vector<std::unique_ptr<ParallelTensor>>> result;
  // Compute per-device per-output tensors

from typing import Optional

import pytest
from fastapi import Cookie, FastAPI, Header, Path, Query
from fastapi.testclient import TestClient

app = FastAPI()


@app.get("/hidden_cookie")
async def hidden_cookie(
    hidden_cookie: Optional[str] = Cookie(default=None, include_in_schema=False),
):
    return {"hidden_cookie": hidden_cookie}


@app.get("/hidden_header")
async def hidden_header(

			Description: `customize scanner speed (default|slowest|slow|fast|fastest)` + defaultHelpPostfix(Speed),
			Optional:    true,
			Type:        "string",
		},
		config.HelpKV{
			Key:         ExcessVersions,
			Description: `alert per object beyond this many versions` + defaultHelpPostfix(ExcessVersions),
			Optional:    true,
			Type:        "int",
		},
		config.HelpKV{
			Key:         ExcessFolders,

			Description: "Enterprise license for the cluster" + defaultHelpPostfix(config.License),
			Optional:    true,
			Sensitive:   true,
		},
		config.HelpKV{
			Key:         config.APIKey,
			Type:        "string",
			Description: "Enterprise license API key for the cluster" + defaultHelpPostfix(config.APIKey),
			Optional:    true,
			Sensitive:   true,
		},
		config.HelpKV{
			Key:         config.Proxy,

        properties["runtime"] = runtime.get().joinToString(",")
        properties["projects"] = projects.get().joinToString(",")
        optionalProjects.get().takeIf { it.isNotEmpty() }?.let { optional ->
            properties["optional"] = optional.joinForProperties()
        }
    }

    private
    fun FileSystemLocation.toGradleModuleName(): String = asFile.name.run { substring(0, lastIndexOf('-')) }

    private

```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009.py!}
```

Sử dụng `Optional[str]` thay cho `str` sẽ cho phép trình soạn thảo giúp bạn phát hiện các lỗi mà bạn có thể gặp như một giá trị luôn là một `str`, trong khi thực tế nó rất có thể là `None`.

from typing import Optional


def say_hi(name: Optional[str]):

from typing import Dict, List, Optional, Tuple

import pytest
from fastapi import FastAPI, Query
from pydantic import BaseModel


def test_invalid_sequence():
    with pytest.raises(AssertionError):
        app = FastAPI()

        class Item(BaseModel):
            title: str

        @app.get("/items/")
        def read_items(q: List[Item] = Query(default=None)):
            pass  # pragma: no cover