"""
        if self.cid is not None:
            fetcher = self._create_credentials_fetcher()
            return RefreshableCredentials.create_from_metadata(
                metadata=fetcher(),
                refresh_using=fetcher,
                method=self.METHOD,
            )
        else:
            return None

    def _create_credentials_fetcher(self):
        method = self.METHOD

from fastapi.testclient import TestClient
from inline_snapshot import snapshot
from pydantic import BaseModel, HttpUrl

app = FastAPI()


class Invoice(BaseModel):
    id: str
    title: str | None = None
    customer: str
    total: float


class InvoiceEvent(BaseModel):
    description: str
    paid: bool


class InvoiceEventReceived(BaseModel):
    ok: bool

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package csv

import (
	"encoding/xml"
	"errors"
	"fmt"
	"io"
	"strings"
	"unicode/utf8"
)

const (
	none   = "none"
	use    = "use"
	ignore = "ignore"

	defaultRecordDelimiter      = "\n"
	defaultFieldDelimiter       = ","
	defaultQuoteCharacter       = `"`
	defaultQuoteEscapeCharacter = `"`

    assertThat(CharMatcher.none().negate()).isSameInstanceAs(CharMatcher.any());
    assertThat(CharMatcher.any().negate()).isSameInstanceAs(CharMatcher.none());

    assertThat(CharMatcher.any().and(WHATEVER)).isSameInstanceAs(WHATEVER);
    assertThat(CharMatcher.any().or(WHATEVER)).isSameInstanceAs(CharMatcher.any());

    assertThat(CharMatcher.none().and(WHATEVER)).isSameInstanceAs(CharMatcher.none());

from fastapi import Depends, FastAPI

app = FastAPI()


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class CommonQueryParams:
    def __init__(self, q: str | None = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit


@app.get("/items/")
async def read_items(commons: Annotated[Any, Depends(CommonQueryParams)]):

from fastapi import FastAPI
from fastapi.openapi.docs import (
    get_redoc_html,
    get_swagger_ui_html,
    get_swagger_ui_oauth2_redirect_html,
)

app = FastAPI(docs_url=None, redoc_url=None)


@app.get("/docs", include_in_schema=False)
async def custom_swagger_ui_html():
    return get_swagger_ui_html(
        openapi_url=app.openapi_url,
        title=app.title + " - Swagger UI",

from fastapi.testclient import TestClient

app = FastAPI()


@app.get("/query")
def read_query(q: str | None):
    return q


@app.get("/explicit-query")
def read_explicit_query(q: str | None = Query()):
    return q


@app.post("/body-embed")
def send_body_embed(b: str | None = Body(embed=True)):
    return b


client = TestClient(app)


def test_required_nonable_query_invalid():

Это означает, что `item` может быть `int` или `str`.

#### Возможно `None` { #possibly-none }

Вы можете объявить, что значение может иметь определённый тип, например `str`, но также может быть и `None`.

//// tab | Python 3.10+

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

////

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float = 10.5


items = {
    "foo": {"name": "Foo", "price": 50.2},
    "bar": {"name": "Bar", "description": "The Bar fighters", "price": 62, "tax": 20.2},
    "baz": {
        "name": "Baz",
        "description": "There goes my baz",

public interface Location {

    /**
     * Return the line number where the current event ends,
     * returns -1 if none is available.
     * @return the current line number
     */
    int getLineNumber();

    /**
     * Return the column number where the current event ends,
     * returns -1 if none is available.
     * @return the current column number
     */
    int getColumnNumber();

    /**