pub fn bundle_installer<PB, FE, ADS>(
    builder: &mut AppBuilder<PB>,
    (fetch_engine, assets_database_setup): (FE, ADS)
) -> Result<(), PipelineBuilderError>where
    PB: PipelineBuilder,
    FE: FetchEngine + 'static,
    ADS: FnMut(&mut AssetsDatabase),