Anonymous arguments - Re: comic-book-insult

[Jean Louis]

* Eli Zaretskii <eliz@gnu.org> [2019-09-09 20:14]:
> > Date: Mon, 9 Sep 2019 20:05:53 +0200
> > From: Jean Louis <bugs@gnu.support>
> > 
> > Thanks for explanation of anonymous arguments. Anonymous function is
> > clear, but I did not know of _ and __ arguments.
> > 
> > I cannot find it in the Emacs Lisp manual, is it there?
> 
> It's right there at the end of "Using Lexical Binding".

Cannot find it, help me. I wish to understand it.