///

Das einzig Neue ist `callbacks=invoices_callback_router.routes` als Argument für den *Pfadoperation-Dekorator*. Wir werden als Nächstes sehen, was das ist.

## Dokumentation des Callbacks

Der tatsächliche Callback-Code hängt stark von Ihrer eigenen API-Anwendung ab.

For example you could have a file `main.py` with:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip

The second argument to <a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> is the default value to return.

Je kunt bijvoorbeeld een bestand `main.py` hebben met:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip

Het tweede argument van <a href="https://docs.python.org/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> is de standaardwaarde die wordt geretourneerd.

     * on an SMB server addressed by the <code>SmbFile</code> parameter. See
     * {@link jcifs.smb.SmbFile} for a detailed description and examples of
     * the smb URL syntax. If the second argument is <code>true</code>, then
     * bytes will be written to the end of the file rather than the beginning.
     *
     * @param file
     *            An <code>SmbFile</code> representing the file to write to

						},
					},
				},
				nil,
				[][]uint64{{
					16, 16, 16, 16, 16, 16, 16, 16,
					16, 16, 16, 16, 16, 16, 16, 16,
				}},
			},
			true,
		},
		// More than 1 ellipses per argument for standalone setup.
		{
			"/export{1...10}/disk{1...10}",
			endpointSet{
				[]ellipses.ArgPattern{
					[]ellipses.Pattern{
						{
							Prefix: "",
							Suffix: "",

      </searchConfiguration>

{* ../../docs_src/path_params/tutorial001.py hl[6:7] *}

O valor do parâmetro que foi passado à `item_id` será passado para a sua função como o argumento `item_id`.

Então, se você rodar este exemplo e for até <a href="http://127.0.0.1:8000/items/foo" class="external-link" target="_blank">http://127.0.0.1:8000/items/foo</a>, você verá a seguinte resposta:

```JSON

Mehr erfahren Sie am Ende dieser Seite.

///

## Zusätzliche Argumente für `Field`

Wenn Sie `Field()` mit Pydantic-Modellen verwenden, können Sie ebenfalls zusätzliche `examples` deklarieren:

{* ../../docs_src/schema_extra_example/tutorial002_py310.py hl[2,8:11] *}

	if ns1 != ns2 {
		return fmt.Errorf("Expected number of endpoints %d, seen %d", ns1, ns2)
	}

	for i, cmdLine := range s1.CmdLines {
		if cmdLine != s2.CmdLines[i] {
			return fmt.Errorf("Expected command line argument %s, seen %s", cmdLine,
				s2.CmdLines[i])
		}
	}

	if reflect.DeepEqual(s1.MinioEnv, s2.MinioEnv) {
		return nil
	}

	// Report differences in environment variables.
	var missing []string

// [Writer.CreateHeader], [Writer.CreateRaw], or [Writer.Close].
//
// In contrast to [Writer.CreateHeader], the bytes passed to Writer are not compressed.
//
// CreateRaw's argument is stored in w. If the argument is a pointer to the embedded
// [FileHeader] in a [File] obtained from a [Reader] created from in-memory data,
// then w will refer to all of that memory.