a monoid that keeps track of the monoid usage
move to its own package; add mention regarding threading
rename misleading val name
increasing capacity to prevent any practical overflow
no semicolons
add return type to public methods; move totals to long
make threadsafe and optionally not
replace pow(2, i) by bit shifting
address review comments
split classes into their own files
typo
Merge pull request #311 from julienledem/semigroup_stats

a monoid that keeps track of the monoid usage
make distribution immutable now that it contains mutable counters
Merge pull request #313 from julienledem/semigroup_stats

make distribution immutable now that it contains mutable counters