Create a function that takes a list and returns the product of the largest and second largest number.
product([2, 3, 1, -1, 2]) ➞ 6
# 2 * 3 = 6
product([-2, -2, -1, -1]) ➞ 2
# -2 * - 1 = 2
# Not 1, because you can only use -1 one time.
product([8, 8, 8]) ➞ 64
# 8 * 8 = 64
# You can repeat here because there is only one value.
product([2, 8, 8, 8]) ➞ 16
# 2 * 8 = 16
# Not 64, because you can only use 8 one time.