PyApp seems to be taking the Python world by storm, providing long-awaited click-and-run Python distribution. For developers ...

All you need to do is open the Terminal application and type python to get started (type ctrl+d to exit Python). Learn Python the Hard Way has everything you need to start programming in Python.

This doesn't bother Python, but it should bother you, either because the type annotation needs to be loosened up, or because (as in this case), it's calling the function with the wrong type of ...