sort() returns None

Question

sort() returns None

Accepted Answer

list.sort() is an in-place operation that returns None, not the sorted list. Assigning its return value gives you None. The sorting did happen though - nums itself is now [1, 2, 3]. The classic bug is 'nums = nums.sort()' which destroys your reference to the list. Use sorted(nums) if you need to capture the result.