async def METHOD_NAME(
    self,
    body: Body,
    mimetype: str,
    content_length: int | None,
    options: dict[str, str],
) -> tuple[MultiDict, MultiDict]:
    parser = MultiPartParser(
        self.stream_factory,
        self.charset,
        self.errors,
        cls=self.cls,
        file_storage_cls=self.file_storage_class,
    )
    boundary = options.get("boundary", "").encode("ascii")
    if not boundary:
        raise ValueError("Missing boundary")
    return await parser.parse(body, boundary, content_length)