import itertools


def powerset(L):
    """
    Constructs the power set, 'potenz Menge' of a given list.

    return list: of all possible subsets
    """
    pset = []
    for n in range(len(L) + 1):
        for sset in itertools.combinations(L, n):
            pset.append(sset)
    return pset