Sorting cards by suit and value using Shell Sort

The question description: put a deck of cards in order by suit (in the order spades, heart, clubs, diamonds) and by rank within each suit, with the restriction that the card must be laid out face down in a row, and the only allowed operations are to check the values of two cards and to exchange two cards (keeping them face down).

My solution:

from enum import Enum import random   class Suit(Enum):     __order__ = "spade heart club diamond"     spade = 1     heart = 2     club = 3     diamond = 4   class Card(object):     def __init__(self, suit, value):         assert type(suit) == Suit         assert value > 0 and value < 14         self._suit = suit         self._value = value         self.value = self._get_value()      def _get_value(self):         return self._suit.value * 13 + self._value      def __lt__(self, other):         return self.value < other.value      def __str__(self):         return str((self._suit.name, self._value))  cards = []  for s in Suit:     for i in range(13):         cards.append(Card(s, i+1))   random.shuffle(cards)   def shell_sort(cards):     h = 1     while(h<52/3):         h = 3*h + 1     # h = 30     # should be more than 29?     while(h>0):         for k in range(h, 52):             j = k             while(j >= h and cards[j] < cards[j-h]):                 cards[j], cards[j-h] = cards[j-h], cards[j]                 j -= h         h = int(h / 3)     return cards  sorted_cards = shell_sort(cards)  for c in sorted_cards:     # how to consider the suit, can the suit decrease the compare times?     print(c) 

I think this can be further optimized since there should be no compares among different suits. Can that be integrated in the shell sort without firstly rank the suits (then the values inside)?