def power_set(set):
    """
    Given a set (list with no duplicates), returns a list of all the subsets.
    """
    size = len(set)
    # start with empty set
    result = [[]]
    for i in range(size):
        pivot = [set[i]]
        # generate all possible subsets with each individual element
        # using helper recursive function
        gen_subsets(result, pivot, set[i+1:])
    return result

def gen_subsets(result, base, remainder):
    """
    Given base set and remainder set, generates and appends to result all possible
    subsets (including base) containing base and any of the elements in remainder.
    """
    # Have to append a copy of base, otherwise black magic will happen.
    result.append(base[:])
    # If remainder set is empty, no more subsets. Return.
    if len(remainder) == 0:
        return

    for i in range(len(remainder)):
        # recursive backtracking: add an element from remainder to base, generate subsets
        # and afterwards discard that element
        base.append(remainder[i])
        gen_subsets(result, base, remainder[i+1:])
        base.pop()

    return

hello = [1,2,3]
print(power_set(hello))