Regular for loop vs comprehension — variable leakage

Question

Accepted Answer

A regular for loop does leak its loop variable into the enclosing scope — after the loop ends, i is 2 (the last value from range(3)). A list comprehension does not leak — j is scoped to the comprehension and does not exist afterward, so print(j) raises NameError. Knowing this difference matters when refactoring a for loop into a comprehension or vice versa.