I'd go one step further, I would accept the existence of both typed and non-typed "runtime" versions of Python (i.e. a run-time flag or program argument). Writing a quick script? Reach for the non-typed version. Writing production software? We ought to make sure we're type checking. Default to non-typed to stop beginners breaking their code.

The same with something like JIT vs compiling, I don't want to find out that some edge case a quadrillion loops in has some simple error a compiler could have found.