Для этого мы обновляем Pydantic‑модель `TokenData`, добавляя новое свойство `scopes`.

Валидируя данные с помощью Pydantic, мы можем удостовериться, что у нас, например, именно `list` из `str` со scopes и `str` с `username`.

А не, скажем, `dict` или что‑то ещё — ведь это могло бы где‑то позже сломать приложение и создать риск для безопасности.

编写带有类型标注的标准 Python：

```Python
from datetime import date

from pydantic import BaseModel

# Declare a variable as a str
# and get editor support inside the function
def main(user_id: str):
    return user_id


# A Pydantic model
class User(BaseModel):
    id: int
    name: str
    joined: date
```

可以像这样来使用：

```Python
my_user: User = User(id=3, name="John Doe", joined="2018-07-19")

from typing import Optional, Union

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: Optional[str] = None


class OtherItem(BaseModel):
    price: int


@app.post("/items/")
def save_union_body(item: Union[OtherItem, Item]):
    return {"item": item}


client = TestClient(app)

    public final void writeUTF(final String str) throws SmbException {
        final int len = str.length();
        int ch, size = 0;
        byte[] dst;

        for (int i = 0; i < len; i++) {
            ch = str.charAt(i);
            size += ch > 0x07F ? ch > 0x7FF ? 3 : 2 : 1;
        }
        dst = new byte[size];
        writeShort(size);
        Encdec.enc_utf8(str, dst, 0, size);
        write(dst, 0, size);

Para isso, nós atualizamos o modelo Pydantic `TokenData` com a nova propriedade `scopes`.

Ao validar os dados com o Pydantic nós podemos garantir que temos, por exemplo, exatamente uma `list` de `str` com os escopos e uma `str` com o `username`.

No lugar de, por exemplo, um `dict`, ou alguma outra coisa, que poderia quebrar a aplicação em algum lugar mais tarde, tornando isso um risco de segurança.

    return f"bar_{route.name}"


def custom_generate_unique_id3(route: APIRoute):
    return f"baz_{route.name}"


class Item(BaseModel):
    name: str
    price: float


class Message(BaseModel):
    title: str
    description: str


def test_top_level_generate_unique_id():
    app = FastAPI(generate_unique_id_function=custom_generate_unique_id)
    router = APIRouter()

        openapi_url=app.openapi_url,
        title=app.title + " - ReDoc",
        redoc_js_url="/static/redoc.standalone.js",
    )


@app.get("/users/{username}")
async def read_user(username: str):

{* ../../docs_src/response_model/tutorial004_py310.py hl[9,11:12] *}

* `description: Union[str, None] = None` (o `str | None = None` en Python 3.10) tiene un valor por defecto de `None`.
* `tax: float = 10.5` tiene un valor por defecto de `10.5`.
* `tags: List[str] = []` tiene un valor por defecto de una list vacía: `[]`.

pero podrías querer omitirlos del resultado si no fueron en realidad almacenados.

        return getName();
    }

    static String unescape(final String str) throws NumberFormatException, UnsupportedEncodingException {
        char ch;
        int i, j, state, len;
        char[] out;
        final byte[] b = new byte[1];

        if (str == null) {
            return null;
        }

        len = str.length();
        out = new char[len];
        state = 0;

}

// QuoteTo write quoted value to writer
func (stmt *Statement) QuoteTo(writer clause.Writer, field interface{}) {
	write := func(raw bool, str string) {
		if raw {
			writer.WriteString(str)
		} else {
			stmt.DB.Dialector.QuoteTo(writer, str)
		}
	}

	switch v := field.(type) {
	case clause.Table:
		if v.Name == clause.CurrentTable {
			if stmt.TableExpr != nil {
				stmt.TableExpr.Build(stmt)