returns a random string of len=<length> from <alphabet>
    I have no idea why this is named random_nonce

def random_nonce(length=64, alphabet=None):
    """
    returns a random string of len=<length> from <alphabet>
    I have no idea why this is named random_nonce
    """
    assert length > 0
    if alphabet is None:
        alphabet = ALPHABET_16
    return ''.join( [alphabet[random.randint(0, len(alphabet) - 1)] for _ in range(length)] )