pub fn draw_congestion_plot<'a, DB: DrawingBackend + 'a>(
params: &PlotParameters,
axis: &XYMinMax<u64>,
ss: &SeriesStore,
ds: &Datastore,
plot: &DrawingArea<DB, Shift>,
) -> ChartContext<'a, DB, Cartesian2d<RangedCoordf64, RangedCoordu64>>