I think i've found a bag! Please, check it!

def checkio(array):
sum = 0
for i in array[0::2]:
    sum += i
return sum * array[-1]

Interesting, that after running i get right answer, but also it writes:

"IndexError: list index out of range checkio, 5 <module>, 15"

I think this is a real bug, because when i test it on my computer everything is ok! Also i don't think that it is out of range, because i have seen, that if you write negative number as index, for example: -1, you will start finding value from end. Help me, please!