{!> ../../docs_src/python_types/tutorial008b_py39.py!}
```

////

In both cases this means that `item` could be an `int` or a `str`.

#### Possibly `None` { #possibly-none }

You can declare that a value could have a type, like `str`, but that it could also be `None`.

In Python 3.6 and above (including Python 3.10) you can declare it by importing and using `Optional` from the `typing` module.

```Python hl_lines="1  4"

Your response model could have default values, like:

{* ../../docs_src/response_model/tutorial004_py310.py hl[9,11:12] *}

* `description: Union[str, None] = None` (or `str | None = None` in Python 3.10) has a default of `None`.
* `tax: float = 10.5` has a default of `10.5`.
* `tags: List[str] = []` has a default of an empty list: `[]`.

from fastapi import FastAPI

app = FastAPI()


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


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

### Dockerfile { #dockerfile }

Now in the same project directory create a file `Dockerfile` with:

```{ .dockerfile .annotate }
# (1)!

@SuppressWarnings("checkstyle:InterfaceIsType")
public interface Language extends ExtensibleEnum {

    /**
     * The "none" language. It is not versioned, family is same to itself, and compatible with itself only.
     * In turn, every {@link Language} implementation must be compatible with {@code NONE} language.
     */
    Language NONE = language("none");

    /**
     * The "resources" language. This is used for files such as images to provide in the output.

                """
            ),
        ] = None,
        description: Annotated[
            Optional[str],
            Doc(
                """
                Security scheme description.

                It will be included in the generated OpenAPI (e.g. visible at `/docs`).
                """
            ),
        ] = None,
        auto_error: Annotated[
            bool,
            Doc(

 *
 */
@Deprecated
public final class ArtifactStatus implements Comparable<ArtifactStatus> {
    /**
     * No trust - no information about status.
     */
    public static final ArtifactStatus NONE = new ArtifactStatus("none", 0);

    /**
     * No trust - information was generated with defaults.
     */
    public static final ArtifactStatus GENERATED = new ArtifactStatus("generated", 1);

    /**

### Target language

Translate to Ukrainian (українська).

Language code: uk.

### Grammar and tone

1) Use polite/formal address consistent with existing Ukrainian docs (use “ви/ваш”).
2) Keep the tone concise and technical.

### Headings

1) Follow existing Ukrainian heading style; keep headings short and instructional.
2) Do not add trailing punctuation to headings.

### Quotes

     */
    @InputFile
    @PathSensitive(PathSensitivity.NONE)
    public abstract RegularFileProperty getHtmlFile();

    /**
     * The decorated HTML file
     */
    @OutputFile
    public abstract RegularFileProperty getDestinationFile();

    /**
     * JQuery used by the added decoration
     */
    @InputFiles
    @PathSensitive(PathSensitivity.NONE)
    public abstract ConfigurableFileCollection getJquery();

            """
        ),
    ] = None,
    init_oauth: Annotated[
        Optional[dict[str, Any]],
        Doc(
            """
            A dictionary with Swagger UI OAuth2 initialization configurations.
            """
        ),
    ] = None,
    swagger_ui_parameters: Annotated[
        Optional[dict[str, Any]],
        Doc(
            """

    do {
      System.runFinalization();
      if (predicate.isDone()) {
        return;
      }
      CountDownLatch done = new CountDownLatch(1);
      createUnreachableLatchFinalizer(done);
      await(done);
      if (predicate.isDone()) {
        return;
      }
    } while (System.nanoTime() - deadline < 0);
    throw formatRuntimeException(