[xmonad] XMonad.StackSet doesn't have focusLast

[Ted Zlatanov]

Similar to focusDown and focusUp in XMonad.StackSet, is there a way to
do focusLast?  I am learning Haskell but don't know it well enough to
write that function yet.

I saw something promising in
http://xmonad.org/xmonad-docs/xmonad-contrib/src/XMonad-Hooks-InsertPosition.html
(with a specific note wondering if focusLast should go into StackSet)
but don't know if it will work.  Any help is most welcome.

Thanks
Ted