app = FastAPI()


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


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

In this case, it is an `async` function.

---

You could also define it as a normal function instead of `async def`:

{* ../../docs_src/first_steps/tutorial003_py39.py hl[7] *}

/// note

If you don't know the difference, check the [Async: *"In a hurry?"*](../async.md#in-a-hurry){.internal-link target=_blank}.

///

In diesem Fall handelt es sich um eine `async`-Funktion.

---

Sie könnten sie auch als normale Funktion anstelle von `async def` definieren:

{* ../../docs_src/first_steps/tutorial003_py39.py hl[7] *}

/// note | Hinweis

Wenn Sie den Unterschied nicht kennen, lesen Sie [Async: *„In Eile?“*](../async.md#in-a-hurry){.internal-link target=_blank}.

///

```Python
contents = myfile.file.read()
```

/// note | Detalhes Técnicos do `async`

Quando você usa os métodos `async`, o **FastAPI** executa os métodos de arquivo em um threadpool e aguarda por eles.

///

/// note | Detalhes Técnicos do Starlette

<details markdown="1">
<summary>Or use <code>async def</code>...</summary>

If your code uses `async` / `await`, use `async def`:

```Python hl_lines="9  14"
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
async def read_item(item_id: int, q: Union[str, None] = None):

//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package callhome

import (
	"sync"
	"time"

	"github.com/minio/minio/internal/config"
	"github.com/minio/pkg/v3/env"
)

// Callhome related keys
const (
	Enable    = "enable"
	Frequency = "frequency"
)

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

package cmd

import (
	"container/ring"
	"context"
	"io"
	"sync"
	"sync/atomic"

	"github.com/minio/madmin-go/v3"
	"github.com/minio/madmin-go/v3/logger/log"
	"github.com/minio/minio/internal/logger"
	"github.com/minio/minio/internal/logger/target/console"

        }
    }

    /**
     * Test implementation of CommonServerMessageBlockResponse
     */
    private static class TestResponse implements CommonServerMessageBlockResponse {
        private boolean async = false;
        private CommonServerMessageBlockResponse nextResponse;
        private boolean received = false;
        private int errorCode = 0;
        private long mid = 0;
        private Long expiration = null;

Es solo una función estándar que puede recibir parámetros.

Puede ser una función `async def` o una función normal `def`, **FastAPI** sabrá cómo manejarla correctamente.

En este caso, la función de tarea escribirá en un archivo (simulando el envío de un email).

Y como la operación de escritura no usa `async` y `await`, definimos la función con un `def` normal:

	trash:   make(map[string]metacache),
}

type metacacheManager struct {
	mu      sync.RWMutex
	init    sync.Once
	buckets map[string]*bucketMetacache
	trash   map[string]metacache // Recently deleted lists.
}

const metacacheMaxEntries = 5000

// initManager will start async saving the cache.
func (m *metacacheManager) initManager() {
	// Add a transient bucket.