ps6_subsets

def generate_all_subsets(hand_string):
    """
    Returns a sequence containing all the substrings of the string hand.

    hand_string: string
    """

    if len(hand_string) == 0:
        return [""]
    subsets = generate_all_subsets(hand_string[1:])
    ans = subsets[:]
    for subset in subsets:
        ans.append(hand_string[0] + subset)
    return ans  # list