with acquire_session() as s:
        yield s


def broken_dep_session() -> Any:
    with acquire_session() as s:
        s.open = False
        yield s


SessionDep = Annotated[Session, Depends(dep_session)]
BrokenSessionDep = Annotated[Session, Depends(broken_dep_session)]

app = FastAPI()


@app.get("/data")
def get_data(session: SessionDep) -> Any:
    data = list(session)
    return data

Since Python 3.9, `Annotated` is a part of the standard library, so you can import it from `typing`.

{* ../../docs_src/python_types/tutorial013_py39.py hl[1,4] *}

Python itself doesn't do anything with this `Annotated`. And for editors and other tools, the type is still `str`.

from typing import Annotated, Union

from fastapi import Body, FastAPI
from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = Field(
        default=None, title="The description of the item", max_length=300
    )
    price: float = Field(gt=0, description="The price must be greater than zero")
    tax: Union[float, None] = None


@app.put("/items/{item_id}")

from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException

app = FastAPI()


class InternalError(Exception):
    pass


def get_username():
    try:
        yield "Rick"
    except InternalError:
        print("We don't swallow the internal error here, we raise again 😎")
        raise


@app.get("/items/{item_id}")
def get_item(item_id: str, username: Annotated[str, Depends(get_username)]):

import gzip
from typing import Annotated, Callable

from fastapi import Body, FastAPI, Request, Response
from fastapi.routing import APIRoute


class GzipRequest(Request):
    async def body(self) -> bytes:
        if not hasattr(self, "_body"):
            body = await super().body()
            if "gzip" in self.headers.getlist("Content-Encoding"):
                body = gzip.decompress(body)
            self._body = body

//// tab | Python 3.9+

```Python hl_lines="1"
async def needy_dependency(fresh_value: Annotated[str, Depends(get_value, use_cache=False)]):
    return {"fresh_value": fresh_value}
```

////

//// tab | Python 3.9+ sin Anotaciones

/// tip | Consejo

Prefiere usar la versión `Annotated` si es posible.

///

```Python hl_lines="1"

import time
from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException
from fastapi.responses import StreamingResponse
from sqlmodel import Field, Session, SQLModel, create_engine

engine = create_engine("postgresql+psycopg://postgres:postgres@localhost/db")


class User(SQLModel, table=True):
    id: int | None = Field(default=None, primary_key=True)
    name: str


app = FastAPI()


def get_session():

from typing import Annotated, Union

import pytest
from dirty_equals import IsOneOf, IsPartialDict
from fastapi import Body, FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel, Field

from .utils import get_body_model_name

app = FastAPI()

# =====================================================================================
# Without aliases

from typing import Annotated, Optional

import pytest
from fastapi import Body, FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel, Field

from .utils import get_body_model_name

app = FastAPI()

# =====================================================================================
# Without aliases


@app.post("/optional-str", operation_id="optional_str")

from typing import Annotated

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


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


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Annotated[
        Item,
        Body(
            openapi_examples={