# class "feature"
    assert is_uploadfile_sequence_annotation(Union[list[str], list[UploadFile]])


def test_serialize_sequence_value_with_optional_list():
    """Test that serialize_sequence_value handles optional lists correctly."""
    from fastapi._compat import v2

    field_info = FieldInfo(annotation=Union[list[str], None])
    field = v2.ModelField(name="items", field_info=field_info)

            should start (the code before `yield`) and when it should end (the code
            after `yield`).

            * `"function"`: start the dependency before the *path operation function*
                that handles the request, end the dependency after the *path operation
                function* ends, but **before** the response is sent back to the client.

            Optional[Sequence[Callable[[], Any]]],
            Doc(
                """
                A list of startup event handler functions.

                You should instead use the `lifespan` handlers.

                Read more in the [FastAPI docs for `lifespan`](https://fastapi.tiangolo.com/advanced/events/).
                """
            ),
        ] = None,
        on_shutdown: Annotated[

        * [Override the default exception handlers](https://fastapi.tiangolo.com/tutorial/handling-errors/#override-the-default-exception-handlers).
        * [Reuse **FastAPI's** exception handlers](https://fastapi.tiangolo.com/tutorial/handling-errors/#reuse-fastapis-exception-handlers).
    * PR [#273](https://github.com/tiangolo/fastapi/pull/273).