On Apr 23, 2012, at 9:52 AM, Steven D'Aprano wrote:

However, the discoverability of this solution is essentially zero

That exact code has been in the documentation for years:

def powerset(iterable):
    "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
    s = list(iterable)
    return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))

The whole purpose of the itertools recipes are to teach how

the itertools can be readily combined to build new tools.

http://docs.python.org/library/itertools.html#module-itertools

Raymond