Piriformis Stretch

Hello all

 I have been sent via e-mail a description of a Piriformis stretch, but for the life of me I cannot work out what it should look like as there are no diagrams.  Can anyone offer any further guidance or a link to a diagram to this stretch ?

"Place the right knee on the ground roughly in line with your left shoulder. The right foot should be just in front of the left knee.

Press your hips towards the ground so that your bodyweight is on your right leg.

As you move down the right knee comes closer to the left shoulder. You should feel a pull deep in the right hip / buttocks. "

 Many thanks in advance

DM