There are two question by following:
First: I want to know the option's natrual value,the the mathematica tell me that it is "Automatic".When I try to get it like this:
In:= Clear["`*"] AbsoluteOptions[Limit[Abs[x - 1], x -> 1], Direction] Out= AbsoluteOptions[0, Direction]
It's a pity.
Second: About the "Pruning",I have some confusion.Let me take a look the picture.
(you can get the picture easily by seaching the "Pruning" in the documents)
It was not my intention.I want to removes 60 pixels from each branch.But actrually the removing is 15 per branch.This is the "Wolfram Documents" description.