This is L system fractals with branches demo. More info about L systems can be found here: https://en.wikipedia.org/wiki/L-system
In this demo, each rule has 1/3 chance to be chosen and applied.
F: During last recursion step, line is drawn and pointer is moved forward at end of the line.
+: Rotation transform is applied clockwise.
-: Rotation transform is applied anti-clockwise.
[: Pointer and rotation transform is pushed onto stack.
]: Pointer and rotation transform is popped from stack.