def METHOD_NAME(data_source):
    # type: (Optional[Text]) -> str
    """
    Finds the data source URL using the provided data source identifier.
    :returns: found URL, 'default' data source if not found, or current weaver WPS Rest API base URL if `None`.
    """
    if data_source is None:
        # get local data source
        return get_wps_restapi_base_url(get_settings())
    data_sources = fetch_data_sources()
    return data_sources[data_source if data_source in data_sources else get_default_data_source(data_sources)]["ades"]