\pgfkeys{/pgf/declare function/ignore spaces=true}
\pgfmathdeclarefunction{test}{1}{
    \pgfmathparse{sin(#1)}
}
\pgfkeys{/pgf/declare function/ignore spaces=false}

\begin{filecontents}{auxhook.sty}
\NeedsTeXFormat{LaTeX2e}
\RequirePackage{xparse}
\ProvidesExplPackage {auxhook} {2020/09/03} {v1.7}
  {draft!!!!! Hooks for auxiliary files (HO)}

% to make KOMA happy ...
\let\@beginmainauxhook\relax
\let\@beginpartauxhook\relax

\NewDocumentCommand\AddLineBeginMainAux{m}
  {
    \clist_if_in:NnT \g__hook_execute_immediately_clist {begindocument}
      {
        \if@filesw
         \PackageInfo{auxhook}
           {
             \@backslashchar AddLineBeginMainAux~comes~a~little~late,

The CSLaTeX package is obsolete and it will be maintained no more.
This is our decision discussed on the CSTeX list

  groups.google.com/forum/?fromgroups#!forum/cz.comp.cstex

in October 2012.

The last two changes was done by Petr Olsak in Oct.2012.

\begin{document}
\newcommand{\Angle}{250}
\tdplotsetmaincoords{170+10*cos(\Angle)}{\Angle}
\begin{tikzpicture}[tdplot_main_coords,line cap=round,line join=round,
	declare function={PHI=(1+sqrt(5))/2;}]
  \path[tdplot_screen_coords,use as bounding box] (-4,-4) rectangle (4,4);
  % light source
  \path[overlay] ({-sqrt(1/6)},{sqrt(3/6)},{sqrt(2/6)})  coordinate (L);
  % base color
  \colorlet{mypolyhedroncolor}{blue}
  % draw the d20
  \path[scale=2,transform shape] pic{icosahedron};
\end{tikzpicture}

\RequirePackage{l3pdf}
\ExplSyntaxOn
\pdf_uncompress:
\ExplSyntaxOff
%
\documentclass[11pt]{report}
\ExplSyntaxOn
\pdf_object_new:nn {blblb} {dict}
\ExplSyntaxOff
\begin{document}
test
\end{document}

\documentclass{article}

\usepackage{color}

\newcount\zz
\begin{document}

\loop
\advance\zz1
\typeout{\the\zz}
\ifodd\zz\color{red}\else\color{blue}\fi
x
\ifnum\zz<10000
\repeat

\end{document}

\documentclass{beamer}

\begin{document}
\begin{frame}{Frame Title}
Define r.v.\@ $Y_r = \sum_{j, f_j>0}I_{r,j}$. That is the number of elements in the stream that have at least $r$ zeros in their tail.

\pause
Let $T$ be the final value of $z$
\begin{align*}
\visible<.->{Y_r >0 \text{ iff }} &\visible<.->{T \geq r}\\
\visible<+(1)->{Y_r=0 \text{ iff }} &\visible<.(1)->{T \leq r-1}
\end{align*}
\pause
\[
\mathbb{E}(I_{r,j}) = \Pr(zeros(h(j)) \geq r) = \Pr(2^r \text{ divides } h(j))
\]
\end{frame}

\def\ImageScale{0.075} % <----- !
\def\ImageLeft{\UseImage{cmHgI}}
\def\ImageRight{\UseImage{cmHgI}}

\documentclass[
fontsize=10pt
%]{book}
]{scrbook}
\usepackage{tikz}

\newsavebox{\mybox}

\begin{document}

\savebox\mybox{\begin{tikzpicture}
    \draw [rounded corners, fill=green!10] (-4,0) node [anchor=north west]{xXxXxXxXxXxXx} rectangle (4,-3);
    \node[draw] (n1)  { node 1};
    \node[below of=n1, draw] (n2)  { node 1};
    \node[below right of=n2, draw] (n3)  { node 1};
\end{tikzpicture}}
\the\wd\mybox

\end{document}

\RequirePackage{l3pdf}
\ExplSyntaxOn
\pdf_uncompress:
\ExplSyntaxOff
\documentclass{article}
\usepackage{tikz}
\begin{document}
blblbllb
\tikz[opacity=0.3]\fill[red](0,0)rectangle(1,1);
\special{pdf:bxgstate << /CA 0.2 /ca 0.2 >>}
   Transparent\newpage text.
\special{pdf:exgstate}%
\end{document}

\def\empty{}
\def\test{\testaux\empty}
\def\testaux#1\endtest{... do something with \detokenize{#1} ...}

\tt\test{abc}\endtest

\bye

\def\empty{}
\def\test{\testaux\empty}
\def\testaux#1\endtest{\expandafter\textauxi\expandafter{#1}}
\def\textauxi#1{... do something with \detokenize{#1} ...}

\tt\test{abc}\endtest

\bye