Python random list

I'm new to Python, and have some problems with creating random lists.

I'm using random.sample(range(x, x), y).

I want to get 4 lists with unique numbers, from 1-4, so I have been using this

a = random.sample(range(1, 5), 4)
b = random.sample(range(1, 5), 4)
c = random.sample(range(1, 5), 4)
d = random.sample(range(1, 5), 4)

So I get for example

a = 1, 3, 2, 4
b = 1, 4, 3, 2
c = 2, 3, 1, 4
d = 4, 2, 3, 1

How can I make it that the column are also unique?