1a[start:stop] # items start through stop-1
2a[start:] # items start through the rest of the array
3a[:stop] # items from the beginning through stop-1
4a[:] # a copy of the whole array
1a[-1] # last item in the array
2a[-2:] # last two items in the array
3a[:-2] # everything except the last two items
4