If it was in a type annotation we could have used the vertical bar, as:

```Python
some_variable: PlaneItem | CarItem
```

But if we put that in the assignment `response_model=PlaneItem | CarItem` we would get an error, because Python would try to perform an **invalid operation** between `PlaneItem` and `CarItem` instead of interpreting that as a type annotation.

```

</div>

/// tip

With `pwdlib`, you could even configure it to be able to read passwords created by **Django**, a **Flask** security plug-in or many others.

So, you would be able to, for example, share the same data from a Django application in a database with a FastAPI application. Or gradually migrate a Django application using the same database.

{* ../../docs_src/openapi_webhooks/tutorial001_py310.py hl[9:12,15:20] *}

The webhooks that you define will end up in the **OpenAPI** schema and the automatic **docs UI**.

/// info

The `app.webhooks` object is actually just an `APIRouter`, the same type you would use when structuring your app with multiple files.

        )


class OAuth2(SecurityBase):
    """
    This is the base class for OAuth2 authentication, an instance of it would be used
    as a dependency. All other OAuth2 classes inherit from it and customize it for
    each OAuth2 flow.

    You normally would not create a new class inheriting from it but use one of the
    existing subclasses, and maybe compose them if you want to support multiple flows.

Depending on your use case, you might prefer to use a different library, but if you asked me, I would probably suggest you try **Strawberry**.

Here's a small preview of how you could integrate Strawberry with FastAPI:

{* ../../docs_src/graphql_/tutorial001_py310.py hl[3,22,25] *}

You could load it at the top level of the module/file, but that would also mean that it would **load the model** even if you are just running a simple automated test, then that test would be **slow** because it would have to wait for the model to load before being able to run an independent part of the code.

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial008b_py310.py!}
```

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`.

//// tab | Python 3.10+

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

import jcifs.internal.smb2.rdma.RdmaMemoryRegion;

/**
 * DiSNI memory region implementation.
 *
 * This class would integrate with DiSNI to provide registered
 * memory regions for high-performance RDMA operations.
 *
 * Note: This is a skeleton implementation. A real implementation would
 * require proper DiSNI integration with actual memory registration.
 */
public class DisniMemoryRegion extends RdmaMemoryRegion {

    # For coverage
    # TODO: in theory this would allow declaring types that could be lists of bytes
    # to be read from files and other types, but I'm not even sure it's a good idea
    # to support it as a first class "feature"
    assert is_bytes_sequence_annotation(list[str] | list[bytes])


def test_is_uploadfile_sequence_annotation():
    # For coverage
    # TODO: in theory this would allow declaring types that could be lists of UploadFile

        Did you *actually* encounter the need for this feature in a real-world scenario, or is it
        just a feature that seems like a sensible addition to Guava?


        Before new features get added to Guava, we really want to be sure that it's for a use case
        that actually comes up in the real world. We want to hear the real-world use case so the