Hi again @dosisod,

One thing I'd like to suggest is adding performance checks.

1. Certain kinds of loops will benefit from being chained using itertools.chain, and in general itertools offers better performance in many cases.
2. Other things are using the builtins, filter, map and reduce, which can be significantly faster than simple python code because of pythons native optimizations.
3. Usage of sets for lookup (in checks, is dramatically faster than list/tuple lookup).