Using recursion, the fractal graph can be easily morph into completely different shape and form, a sleight of hand, and unlimited variations. If you are interested in this topic, just Google it.
A popular but simple recursive 2D Fractal Art is chosen for this exercise. We are to make some addition to this given pattern() recursive function. In the mean time to retain, i.e. keep the original graph. We are to add two straight lines as the graph’s progression boundary. This is for us to see the direction of progression (or digression.)
Instead of the actual fine envelope, I have simplified the requirement to just two straight lines on the outside as the envelope, right and left both sides. These two border straight lines were determined by the two outermost points on the graph’s progression track.