Because you're calling get_guess from verify_guess, and verify_guess is called from get_guess you've introduced recursion into your solution. http://en.wikipedia.org/wiki/Recursion#Recursion_in_computer_science

This isn't a bad thing, but you mightn't be aware of some of the side effects. Each time there's an invalid guess get_guess gets popped onto the call stack. Then when there's a valid guess they all have to complete and check_guess will be run each time resulting in output something like this...

Great scott you got it - Congratulations!

Great scott you got it - Congratulations!

Great scott you got it - Congratulations!

Great scott you got it - Congratulations!