Push to an array, but at the beginning

I know this is probably a simple question, but i’ve had a bit to drink and can’t come up with a good solution.

I want to be able to do the same as the push function on array, but it adds to the start of the array. I assume i’ll need a custom function to do it, but have so far just failed.

example:

a is an array [[1,1,1,1],[2,2,2,2],[3,3,3,3]]
and i want to push [0,0,0,0] into the start so that it becomes [[0,0,0,0],[1,1,1,1],[2,2,2,2],[3,3,3,3]]

Am i missing an obvious trick here? Any help would be appreciated.