JuniorTheoryCommon

What does the program print?

Python

def evens(limit):
    for n in range(0, limit, 2):
        yield n


g = evens(7)
print(sum(g), sum(g))

12 0

Expecting 12 12, as if g started over like a list: a generator gives its values once, and the first sum took them all, so the second sees none.
Expecting an error or None from the second sum: an exhausted generator acts as an empty iterable, and the sum of nothing is 0.

JuniorTheoryCommon

Python

def evens(limit):
    for n in range(0, limit, 2):
        yield n


g = evens(7)
print(sum(g), sum(g))

12 0

Expecting 12 12, as if g started over like a list: a generator gives its values once, and the first sum took them all, so the second sees none.
Expecting an error or None from the second sum: an exhausted generator acts as an empty iterable, and the sum of nothing is 0.