Hi all, I've got a question. A really quick, easy-to-answer question,
if I'm lucky ;)

I have an array of arrays:

a = [[ 1, 2, 3, 4],
     [ 5, 6, 7, 8],
     [ 9,10,11,12],
     [13,14,15,16]]

I've already borrowed code from the Matrix class to select sub-arrays
of this array:

a1 = [[1,2],[5,6]]
b1 = [[3,4],[7,8]]
a2 = [[9,10],[13,14]]
b2 = [[11,12],[15,16]]

and I can easily rotate those, but now I'm not sure on how to put them
back together like so:

[a1][b1]
[a2][b2]

If anyone knows a good way to do this, it would be greatly appreciated.

Thanks again!