Which method retrieves but does not remove the element from the top of a stack?

Which Python feature allows for the extension of existing classes or modules without modifying their source code?

Which algorithm is designed to sort elements by recursively dividing the list into halves, sorting each half, and merging them?

Which principle is essential for ensuring that AI systems can be audited and evaluated by independent parties?

Which commenting practice is recommended for marking tasks or features that need to be completed or reviewed later?