Learn/Python/Python — Advanced/Architecture: Boundaries That Earn Their Keep/Checkpoint: Architecture/Injected checkout serviceInjected checkout serviceChallenge on lesson: Checkpoint: ArchitectureInstructionsCodeOutputImplement CheckoutService(repo, clock) per the spec: injected clock drives ids; empty carts raise before saving; totals are sums of the cart.Difficulty: advancedSubmitPress Submit to check your solution.Back to lesson: Checkpoint: Architecture