Betrachten wir als einfaches Beispiel eine Dateistruktur ähnlich der in [Größere Anwendungen](../tutorial/bigger-applications.md){.internal-link target=_blank} und [Testen](../tutorial/testing.md){.internal-link target=_blank}:

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

Die Datei `main.py` hätte als Inhalt:

{* ../../docs_src/async_tests/app_a_py39/main.py *}

      maxUnavailable: {{ .Values.deploymentUpdate.maxUnavailable }}
    {{- end }}
  replicas: 1
  selector:
    matchLabels:
      app: {{ template "minio.name" . }}
      release: {{ .Release.Name }}
  template:
    metadata:
      name: {{ template "minio.fullname" . }}
      labels:
        app: {{ template "minio.name" . }}
        release: {{ .Release.Name }}
        {{- if .Values.podLabels }}

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item, user: User):

from datetime import datetime, time, timedelta
from uuid import UUID

from fastapi import Body, FastAPI

app = FastAPI()


@app.put("/items/{item_id}")
async def read_items(
    item_id: UUID,
    start_datetime: datetime = Body(),
    end_datetime: datetime = Body(),
    process_after: timedelta = Body(),
    repeat_at: time | None = Body(default=None),
):
    start_process = start_datetime + process_after

from enum import Enum

from fastapi import FastAPI


class ModelName(str, Enum):
    alexnet = "alexnet"
    resnet = "resnet"
    lenet = "lenet"


app = FastAPI()


@app.get("/models/{model_name}")
async def get_model(model_name: ModelName):
    if model_name is ModelName.alexnet:
        return {"model_name": model_name, "message": "Deep Learning FTW!"}

    if model_name.value == "lenet":

from typing import Annotated

from fastapi import FastAPI, Path, Query

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(
    *,
    item_id: Annotated[int, Path(title="The ID of the item to get", ge=0, le=1000)],
    q: str,
    size: Annotated[float, Query(gt=0, lt=10.5)],
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})
    if size:
        results.update({"size": size})

from typing import Annotated, Union

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        Union[str, None],
        Query(
            title="Query string",
            description="Query string for the items to search in the database that have a good match",
            min_length=3,
        ),
    ] = None,
):

errors.login.failure = लॉगिन विफल रहा।
errors.app.illegal.transition = अवैध परिवर्तन। कृपया पुनः प्रयास करें।
errors.app.db.already.deleted = इसे किसी अन्य प्रक्रिया द्वारा हटाया जा सकता है। कृपया पुनः प्रयास करें।
errors.app.db.already.updated = इसे किसी अन्य प्रक्रिया द्वारा अपडेट किया जा सकता है। कृपया पुनः प्रयास करें।
errors.app.db.already.exists = डेटा पहले से मौजूद है। कृपया पुनः प्रयास करें।

 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.app.web.admin.dict.protwords;

import org.codelibs.fess.app.web.CrudMode;
import org.lastaflute.web.validation.Required;
import org.lastaflute.web.validation.theme.conversion.ValidateTypeFailure;

import jakarta.validation.constraints.Size;

/**

@dataclass
class Item:
    name: str
    price: float
    tags: list[str] = field(default_factory=list)
    description: Union[str, None] = None
    tax: Union[float, None] = None


app = FastAPI()


@app.get("/items/next", response_model=Item)
async def read_next_item():
    return {
        "name": "Island In The Moon",
        "price": 12.99,
        "description": "A place to be playin' and havin' fun",