concurrent is a set of collections and various other things to be used in concurrent environment, such as:
Packages in generic subfolder are meant to be used with gengen. Consult its README for examples, but usually it goes something like this:
gengen github.com/codesenberg/concurrent/generic/histogram float64
After this you might want to fill out appropriate functions in generated files marked with TODO commentaries and remove build tag to get autogenerated test suite.