print-definition.tex

\RequirePackage{fvextra}
\RequirePackage{xcolor}

\newcommand{\printDef}[1]{%
  \begingroup
  \ttfamily
  % output command
  \noindent\hspace*{-\parindent}\color{blue}%
  \textbackslash\Verb*|#1|%
  \normalcolor\par
  % output definition of \cs{#1}
  \toString{#1}%
  \list{}{\leftmargin=2em\topsep=0pt\parsep=0pt\partopsep=0pt}%
  \item[]\expandafter\meaning\csname \csname l_tmpa_tl\endcsname\endcsname
  \endlist
  \endgroup
  \vskip\topsep
}

\newcommand{\printAndRunCode}[1]{%
  \addvspace{2\topsep}%
  \begingroup
  \ttfamily
  \noindent\hspace*{-\parindent}\color{orange}%
  \Verb*|#1|%
  \normalcolor\par
  \endgroup
  #1%
}

% add \string in front of each token in #1
% based on https://tex.stackexchange.com/a/44444
\ExplSyntaxOn
\cs_new:Npn \toString #1
  {
    \tl_set:Nn \l_tmpa_tl {#1}
    \regex_replace_all:nnN { . } { \c{string} \0 } \l_tmpa_tl
    \tl_set:Nx \l_tmpa_tl { \l_tmpa_tl }
  }
\ExplSyntaxOff