[RK]

Nice reference.

1.29 happened to be exactly what I was looking for:

  for subset in itertools.chain(*(itertools.combinations(a, n) for n in range(len(a) + 1)))

I spent way too much time writing a function to come up with these combinations.

[rockymeza]

You can also do

    itertools.chain.from_iterable(itertools.combinations(a, n) for n in range(len(a) + 1))