Prom graph panel histograms

I was just wondering if now that Prometheus has heatmap support, which is awesome by the way, whether or not the graph panel histograms where also possible? It seems like all the logic should be there. Using the Format as: Heatmap and Mode: Series seems to work, however each column is a different series (color), what I’d really like to do is stack a bunch of series.

For reference, what trying to do is stack each endpoints latency for an easy way to see which endpoints contribute to which latency modes. Hope that makes sense.