Advanced form of LINE_P

[komame]

In the on-calc help, you can find: "The advanced form of LINE_P allows the rendering of multiple lines at a time with a potential 3D transformation of the points that define the line. This is mostly used if you have a set of vertices and lines and want to display them all at once (faster)".

Can someone provide a working example of a simple LINE_P call that draws two straight lines?
I've tried with lists and matrices, but nothing seemed to work.