The value-add here is that it compiles to C and therefore the type enforcement is done at compile time. If you are OK with interpreted Python and runtime checking you can use https://github.com/prechelt/typecheck-decorator/
That looks cool! It's pretty different though, it's more like a "design by contract" tool.
I have a similar one, more Python2 style dsl (it supports also function overloading through a kind of pattern matching) https://github.com/alehander42/py-matchete
