I believe Julia is an example of a dynamically-typed language which does perform such checks at run-time - including as part of its support for multiple dispatch.
On a general note I've come across a few cases, when pushing python's type annotations to their limits, that force you to put the type names in string quotes, and that makes the whole thing feel like a hack. It's better than nothing for my use cases, but if I remember correctly both mypy and enforce have problems in common that are probably coming from the way python itself is built, such as self reference in a class definition.
With pep-0563, python3.7, and `from __future__ import annotations` this should no longer be necessary. Those are some pretty detailed caveats, but I have been using it in places where I can and it is so nice.
For actual projects you can use a static type checker like mypy.