def METHOD_NAME(self, file_id: str) -> str:
    """Get a URL for a given media file. Raise a MediaFileStorageError if
    no such file exists.
    """
    media_file = self.get_file(file_id)
    extension = get_extension_for_mimetype(media_file.mimetype)
    return f"{self._media_endpoint}/{file_id}{extension}"