Code just prints out [] with nothing in it

from cards import Card 
import random 



class Game:
    def __init__(self): #grid size
        self.size = 4
        self.card_options = ['dog', 'cat', 'egg', 'tea', # card options 
                             'wii', 'key', 'sun', 'oil']
        self.columns = ['A', 'B', 'C', 'D'] # columns
        self.cards = [] # size 
        self.locations = [] # locations
        for column in self.columns: 
            for num in range (1, self.size + 1):
               self.locations.append(f'{column}{num})')

    def set_cards(self):
        used_locations = []
        for word in self.card_options:
            for i in range(2):  # because each card appears twice
                available_locations = set(self.locations) - set(used_locations)
                random_location = random.choice(list(available_locations))
                used_locations.append(random_location)
                card = Card(word, random_location)
                self.cards.append(card)





# methods 

    def create_row(self, num): 
        row = []
        for column in self.columns:
            for card in  self.cards:
                if card.location == f'{column} {num}':
                    if card.matched: 
                        row.append(str(card))
                    else:
                        row.append('   ')
        return row 

    # create cards 
    # create grid 
    # check for matches
    # check if game has been won
    # run the game

# dunder main 
if __name__ == '__main__': 
    game = Game()
    game.set_cards()
    game.cards[0].matched = True 
    game.cards[1].matched = True 
    game.cards[2].matched = True 
    game.cards[3].matched = True 
    print(game.create_row(1))
    print(game.create_row(2))
    print(game.create_row(3))
    print(game.create_row(4))
    #create game instance