generates 16 cards from the deck of SET and returns all possible winning hands.

set.py

from itertools import product
from itertools import permutations
from random import sample

cards = filter(
    lambda _: all(
        [
            # look at all unique values of each property and see if there is 1 or 3
            len(set([a[i][1] for a in _])) in {1,3} for i in range(4)
        ]
    )
    ,
    # Permutation of 4 cards
    permutations(
    # Sample 16 cards    
    sample(
    # Generate a deck
    list(product(
    # Create all possible cards
    *[[prop+value for value in "123"] for prop in "abcd"])), 
    # Sample 16 cards, permute by 4
    16), 4)
)

print(cards)