This immediately writes-off any possible use with a truly simple test, one that just uses ``Subtest``.  I liked @ldoktor 's idea of just hanging a ``tooling`` attribute off of the testing-class.  That could easily be applied to both ``Subtest`` and ``SubSubtest`` through simple composition.  Consider, does this class *really* need to provide the entire sub/subsubtest interface?  I think it could be made simpler by instead just *containing* a sub/subsubtest instance, and calling back to it when needed.  This will also make unittesting and documentation brain-dead easy.