Deck or cards
A Deck of cards is a collection of Card objects:
deck = Deck()
assert isinstance(deck.pop_card(), Card)
If we remove a card from the Deck we can verify that it no longer exists:
deck = Deck()
c = Card(2,3)
deck.remove_card(c)
assert c not in deck.cards
However, another card that we haven't removed, such as the 10 of hearts will still be in the Deck of cards because we haven't removed it.
c2 = Card(2,10)
assert c2 in deck.cards