heroku/umpire — pull request #16 by fabiokung (2013-02-15 21:55:23+00:00)
Title: add an option to use summarized values from multiple sources

This is Librato specific. I don't particularly love using a new param just for that, but I'm open to hear better suggestions.

Graphite supports functions (eg.: `sumSeries`), but Librato doesn't. They provide only two aggregation mechanisms: avg and sum.