list(range(n)) -- I sometimes do this because I never can remember if they have finally gotten around to making range a generator yet, and better safe than sorr

list(range(n)) -- I sometimes do this because I never can remember if they have finally gotten around to making range a generator yet, and better safe than sorry. a[:][2:] -- maybe the author doesn't know that any slice returns a new list? Maybe he just wants to be even more mysterious?