You know what? Legs are heavy. So here are a few good-natured students showing two different pulley systems.
The first one is a rope wall pulley. I learned this from Gillian in one of her rope wall classes. It also works on regular rope walls, or just about anything you can attach over your head. You thread the rope through a hook, have your foot in one end, and hoist your leg into the air. Here is Bob demonstrating:
Incidentally, Bob's wife Jane is in the doorway. I really liked to perspective on this one.
As a rope wall isn't always available, you can also use your shoulder for the pulley. As you pull your arm down, your leg goes up. Here is Marisa showing that one:
Thanks to Gillian, Bob, Marisa, and Austin Yoga Tree