Setsum

Setsum is used at run time in 4 crates. It is a direct run-time dependency in 2 crates.

Number of dependers	Setsum version	Downloads/month
3	0.7.0	90
1	0.6.0	0

Depender (with downloads and own rev deps)			Setsum version
320	3	sst		^0.7
150	1	lsmtk		^0.7