Repeating elements in list comprehension

Question

I have this list comprehension:

[[x,x] for x in range(3)]

which results in this list:

[[0, 0], [1, 1], [2, 2]]

but what I want is this list:

[0, 0, 1, 1, 2, 2]

What's the easiest to way to generate this list?

Answer 1

[y for x in range(3) for y in [x, x]]