Why does my simple program ends after runs? : Here is my little program

    import random
    
    liste = []
    char_list = ['a', 'b', "c", "d"]
    
    while True:
    
        random.shuffle(char_list)
        n = ''.join(char_list)
    
        if n in liste:
            continue
        elif n not in liste:
            print(''.join(char_list))
            liste.append(n)
        else:
            break




Why is this program did not stops after gives the list ?