This is a foundation game that illustrates several techniques:

• Game flow is controlled in the main() method and this is called using the best practice using name.
• An infinite loop in the main method that prompts to "Play Again."
• Global scores that are referenced in the function by using the "global" keyword.
• User input validation and looping when an invalid choice is entered. When a valid choice is entered the function (and the loop) exits with the return.

TODO

• Add winner logic to pick_winner()