Originally it was there once, but as new types of curves arrived code got duplicated.

For example, right now it would make sense to refactor that code, but I suspect you have enough to deal with getting the HRV metric stuff working !

Originally posted by @liversedge in #2354 (comment)

I plan to give the above a try at some point since I would allow metrics with custom aggregateWith method s.t. (#4570).