Imagine you have a little robot that holds a pencil. Set it down on a sheet of paper and give it these instructions:

1. Move forward 3 units and turn right.
2. Move forward 1 unit and turn right.
3. Move forward 2 units and turn left.
4. Move forward 1 unit and turn left.
5. Move forward 2 units and turn right.
6. Repeat.

If the robot makes its turns at 90° angles, it will produce this figure:

But, remarkably, if it turns at 120° it will draw this: