def api_url(service: str = "IPublishedFileService",
            function: str = "QueryFiles",
            version: str = "v1") -> str:
    """
    Builds a steam web API url.
    :param service: The steam service to attach to.
    :param function: The function to call.
    :param version: The API version.
    :return: The built URL.
    """
    return "https://api.steampowered.com/%s/%s/%s/" % (
        service, function, version
    )