def test_intsum():
g = gen.intsum()
assert next(g) == 0
assert next(g) == 1
assert next(g) == 3
assert next(g) == 6
assert next(g) == 10
assert next(g) == 15
def test_intsum():
g = gs.intsum()
for val in [0, 1, 3, 6, 10]:
assert next(g) == val