You're on assignment part 1/2 for this lesson.
Recursion Review
-- xkcd
I hate explaining jokes, but in case you don't get the comic: The joke is that the characters within the Dungeons and Dragons game are also playing their own Dungeons and Dragons game. Maybe their character's game of DnD also has characters playing DnD, and so on, recursively forever.
Another Example
def print_chars(word, i):
if i == len(word):
return
print(word[i])
print_chars(word, i + 1)
print_chars("Hello", 0)
# H
# e
# l
# l
# o