Very confusing code for tree generation

[bunabyt3]

I've been trying to change the tree shape, but I've run into this:

I can't understand it at all. Is there any documentation on this code? I can't understand it by reading it.

[JohnyDaison]

It's not that complicated, it's just creating a random blob of leaves which tapers to the top and bottom. Refactoring it would make it much easier to understand.