Start with iter()
built-in to get iterator over iterable and use next()
to get elements one by one until StopIteration
is raised signifying the end:
s = {1, 2} # or list or generator or even iterator
i = iter(s) # get iterator
a = next(i) # a = 1
b = next(i) # b = 2
c = next(i) # raises StopIteration