Function render_simple_generator 

fn render_simple_generator<'scope>(
    generator: Box<dyn Generator>,
    tick_micros: Option<u64>,
    as_of: MzOffset,
    up_to: MzOffset,
    scope: Scope<'scope, MzOffset>,
    config: &RawSourceCreationConfig,
    committed_uppers: impl Stream<Item = Antichain<MzOffset>> + 'static,
    output_map: BTreeMap<LoadGeneratorOutput, Vec<usize>>,
) -> (BTreeMap<GlobalId, StackedCollection<'scope, MzOffset, Result<SourceMessage, DataflowError>>>, StreamVec<'scope, MzOffset, Infallible>, StreamVec<'scope, MzOffset, HealthStatusMessage>, Vec<PressOnDropButton>)