Python 21-Game Easy AI

I want a clean, well-commented Python script that lets a human user play the classic “21 Number Game” against the computer. For this build the computer only needs to play on an easy, beginner-friendly level rather than the unbeatable variant, so new players can learn the flow of the game without feeling overwhelmed.

Core requirements
• Game counts up from 1 to 21; whoever is forced to say “21” loses.
• On each turn a player may speak 1, 2, or 3 consecutive numbers.
• The human plays first.
• After the result is shown, the user can choose to restart and play again without quitting the program.

I’m happy with a straightforward command-line experience, but if you already have lightweight ways to wrap a minimal GUI or web front-end I’m open to hearing them.

Deliverable
• A single .py file runnable with Python 3.x that meets the above rules, displays clear prompts and results, and is easy for me to tweak later.
• Brief README explaining how to run it and how your “easy” logic works.

Acceptance
If I can run python game21.py, play through several rounds, restart at will, and clearly see the computer making non-optimal moves suited to beginners, the job is done.