Question 1

sorted() with key function

Accepted Answer

The `key=len` argument sorts by string length: 'fig' (3), 'date' (4), 'apple' (5), 'banana' (6). Python's sort is stable, so elements with the same length keep their original relative order. The key function is applied once per element and the results are used for comparison - the actual strings are what get returned.

Question 2

map() return type

Accepted Answer

Both `map()` and `filter()` return lazy iterators, not lists. You have to wrap the result in `list()` to get a concrete sequence. This matters in practice because iterating the map object a second time gives you nothing - it's exhausted. If you need to reuse the result, convert to a list first.

Question 3

Lambda return value

Accepted Answer

A lambda is just an anonymous function. `lambda x: x * 2` creates a function that multiplies its argument by 2, and calling it with 5 returns 10. The result is printed directly, so you see 10 - not the function object or None.