How do I install the Unity Books Lens, and how do I use it?

I read that there is a Unity Book Lens available. How do I install it and how do I use it?

The Google Books Lens can currently be found in a PPA by its author, and currently have a note that These builds may have bugs, be unstable, try to eat your kitten.

To install add the PPA ppa:davidc3/books-lens (How to Add a PPA) and then install unity-books-lens from the software center.

After this, you need to log out and log back (or run unity --replace) in for the lens to show up and work correctly.

The lens uses the shortcut Super-b to show the lens.

Alternative method

sudo add-apt-repository ppa:davidc3/books-lens

sudo apt-get update && sudo apt-get install unity-lens-books