How to get numbers out of a 2D array to a 1D array

I have an argument that passes me a 2D array and I want to get the numbers from that array and put them on a normal array.

The argument passed to me = ([1, 3, 2], [5, 2, 1, 4], [2, 1])
What I want to do = [1, 3, 2, 5, 2, 1, 4, 2, 1]

Thanks in advance, I think I’m having a brain fart over here!