How to write replace string for object which will be substituted? [regexp]

[Ryniek90]

> 2) If you really want to learn regexes, get a copy of _Mastering Regular
> Expressions_ by Friedl (either 2nd or 3rd edition)
>   

I made preview of that book, but some pages are disabled from preview. 
Has that book topics about Python regexp's?
If so, i must buy it.