from random import choice

possibilities = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 'a', 'b', 'c', 'd', 'e']

winning_ticket = []
print("Let's see what the winning ticket is...")

# We don't want to repeat winning numbers or letters, so we'll use a
#   while loop.
while len(winning_ticket) < 4:
    pulled_item = choice(possibilities)

    # Only add the pulled item to the winning ticket if it hasn't
    #   already been pulled.
    if pulled_item not in winning_ticket:
        print(f"  We pulled a {pulled_item}!")
        winning_ticket.append(pulled_item)