from fastapi import Depends, FastAPI

app = FastAPI()


def get_username():
    try:
        yield "Rick"
    finally:
        print("Cleanup up before response is sent")


@app.get("/users/me")
def get_user_me(username: str = Depends(get_username, scope="function")):

Using `Depends(scope="function")`, the exit code after `yield` is executed right after the *path operation function* is finished, before the response is sent back to the client.

And when using `Depends(scope="request")` (the default), the exit code after `yield` is executed after the response is sent.

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

package hash

import (
	"errors"
	"fmt"
)

// SHA256Mismatch - when content sha256 does not match with what was sent from client.
type SHA256Mismatch struct {
	ExpectedSHA256   string
	CalculatedSHA256 string
}

func (e SHA256Mismatch) Error() string {

que les données sont valides, compte tenu de certains paramètres. Par exemple, qu'un champ est un `int`, et non un
string.
Ceci est particulièrement utile pour les données entrantes.

Sans un système de validation des données, vous devriez effectuer toutes les vérifications à la main, dans le code.

              <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED</arg>
              <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED</arg>
              <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED</arg>
              <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED</arg>
              <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED</arg>

You can declare a parameter in a *path operation function* or dependency function with the type `BackgroundTasks`, and then you can use it to schedule the execution of background tasks after the response is sent.

You can import it directly from `fastapi`:

```python
from fastapi import BackgroundTasks
```

	// Buffers sent on out can not be referenced once sent.
	StreamHandlerFn func(ctx context.Context, payload []byte, in <-chan []byte, out chan<- []byte) *RemoteErr

	// StreamHandler handles fully bidirectional streams,
	// There is flow control in both directions.
	StreamHandler struct {
		// Handle an incoming request. Initial payload is sent.

	responses <-chan Response
	cancel    context.CancelCauseFunc

	// Requests sent to the server.
	// If the handler is defined with 0 incoming capacity this will be nil.
	// Channel *must* be closed to signal the end of the stream.
	// If the request context is canceled, the stream will no longer process requests.
	// Requests sent cannot be used any further by the called.
	Requests chan<- []byte

	muxID uint64

{*../../docs_src/python_types/tutorial008.py hl[1,4] *}

Dans cet exemple :

* La variable `prices` est de type `dict` :
    * Les clés de ce dictionnaire sont de type `str`.
    * Les valeurs de ce dictionnaire sont de type `float`.

#### `Optional`

// It does not encrypt empty ETags because such ETags indicate
// that the S3 client hasn't sent an ETag = MD5(object) and
// the backend can pick an ETag value.
func (key ObjectKey) SealETag(etag []byte) []byte {
	if len(etag) == 0 { // don't encrypt empty ETag - only if client sent ETag = MD5(object)
		return etag
	}
	var buffer bytes.Buffer
	mac := hmac.New(sha256.New, key[:])