How to set Unity as default again?

About an hour ago, I asked how I could set Gnome-shell as default desktop interface for Ubuntu replacing Unity, and I was advised to issue this command:

sudo /usr/lib/lightdm/lightdm-set-defaults -s gnome-shell

While this is related to that, it's a different question. Now, how do I set Unity back as default via command line?


sudo /usr/lib/lightdm/lightdm-set-defaults -s ubuntu

sets Unity 3d as default.