[xmonad] How to swap screen in a multihead environment?

I have just started to use xmonad, and it seems to me a great software for multihead screens. At his moment, I am using two physical screens and I would like to use a key binding to do the following thing: "swap screens". By swap screens I mean moving from -the configuration [1 2] to the configuration [2 1] -the configuration [1 3] to the configuration [3 1] -the configuration [4 2] to the configuration [2 4] etc When I say configuration [1 2] I mean that workspace 1 is on left screen and workspace2 in on right screen; and the same idea for [2 1], [1 3], etc Does anybody know how to do this?