\RequirePackage{xparse}[2019-05-03]
\RequirePackage{letltxmacro,l3keys2e}
\def\duckuments@version{0.5}
\def\duckuments@date{2019-10-03}
\ProvidesExplPackage
  {duckuments}          {\duckuments@date}
  {\duckuments@version} {minimal working duckuments}
%    \end{macrocode}
% 
%    \begin{macrocode}
%<@@=duckuments>
%    \end{macrocode}
%
% \subsection{Check for possible problems}^^A>>=
%
% Check whether \file{example-image-duck.pdf} exists.
%    \begin{macrocode}^^A>>=
\file_if_exist:nF { example-image-duck.pdf }
  {%>>=
%    \end{macrocode}
% If the current \cs{jobname} doesn't match \file{example-image-duck} throw an
% error.
%    \begin{macrocode}
    \str_if_eq:VnF \c_sys_jobname_str { example-image-duck }
      {
        \msg_new:nnnn { duckuments } { missing~file }
          {
            The~file~`#1`~can't~be~found.~Make~sure~to~create~it
            \tl_if_empty:nF{#2}{~#2}.
          }
          { Sorry~for~the~inconvenience.~#3 }
        \msg_error:nnnnn { duckuments } { missing~file }
          { example-image-duck.pdf }
          {
            by~compiling~example-image-duck.tex~at~least~once
          }
          {
            If~you~don't~find~the~file~on~your~machine~you~can~use~
            `\duckumentsCreateExampleFiles`~in~your~document~to~produce~a~copy~
            in~the~current~working~directory.
          }
      }
  }%=<<
%    \end{macrocode}^^A=<<
% And do the same for \file{example-image-duck-portrait.pdf}.
%    \begin{macrocode}^^A>>=
\file_if_exist:nF { example-image-duck-portrait.pdf }
  {%>>=
    \str_if_eq:VnF \c_sys_jobname_str { example-image-duck-portrait }
      {
        \msg_if_exist:nnF { duckuments } { missing~file }
          {
            \msg_new:nnnn { duckuments } { missing~file }
              {
                The~file~`#1`~can't~be~found.~Make~sure~to~create~it
                \tl_if_empty:nF{#2}{~#2}.
              }
              { Sorry~for~the~inconvenience.~#3 }
          }
        \msg_error:nnnnn { duckuments } { missing~file }
          { example-image-duck-portrait.pdf }
          {
            by~compiling~example-image-duck-portrait.tex~at~least~once
          }
          {
            If~you~don't~find~the~file~on~your~machine~you~can~use~
            `\duckumentsCreateExampleFiles`~in~your~document~to~produce~a~copy~
            in~the~current~working~directory.
          }
      }
  }%=<<
%    \end{macrocode}^^A=<<
%^^A=<<
%
% \subsection{Variables}^^A>>=
%
% \begin{variable}{\duckuments@randoms}^^A>>=
%   Stores the number of random ducks in \file{example-image-duck.pdf}.
%    \begin{macrocode}
\newcommand*\duckuments@randoms{128}
%    \end{macrocode}
% \end{variable}^^A=<<
%
% \begin{variable}{\l_duckuments_immediate_bool}^^A>>=
%   Stores whether the patch is to be done during package load time.
%    \begin{macrocode}
\bool_new:N \l_duckuments_immediate_bool
%    \end{macrocode}
% \end{variable}^^A=<<
%
% \begin{variable}{\l_duckuments_toc_bool}^^A>>=
%   Stores whether to display a ToC in \cs{duckument}.
%    \begin{macrocode}
\bool_new:N \l_duckuments_toc_bool
%    \end{macrocode}
% \end{variable}^^A=<<
%
% \begin{variable}{\l_duckuments_math_inline_bool}^^A>>=
%   Stores whether to display inline math in \cs{blindduck}.
%    \begin{macrocode}
\bool_new:N \l_duckuments_math_inline_bool
%    \end{macrocode}
% \end{variable}^^A=<<
%
% \begin{variable}{\l_duckuments_math_display_bool}^^A>>=
%   Stores whether to display displayed math in \cs{blindduck}.
%    \begin{macrocode}
\bool_new:N \l_duckuments_math_display_bool
%    \end{macrocode}
% \end{variable}^^A=<<
%
% \begin{variable}{\l_duckuments_blindduck_pars_bool}^^A>>=
%   Stores whether each paragraph of \cs{blindduck} should end with a \cs{par}.
%    \begin{macrocode}
\bool_new:N \l_duckuments_blindduck_pars_bool
%    \end{macrocode}
% \end{variable}^^A=<<
%
% \begin{variable}{\l_duckuments_range_seq}^^A>>=
%   Stores the paragraphs range for \cs{blindduck}.
%    \begin{macrocode}
\seq_new:N \l_duckuments_range_seq
%    \end{macrocode}
% \end{variable}^^A=<<
%
% \begin{variable}{\g_duckuments_blindduck_start_int}^^A>>=
%   Stores the paragraph with which \cs{blindduck} should start.
%    \begin{macrocode}
\int_new:N \g_duckuments_blindduck_start_int
\int_gset:Nn \g_duckuments_blindduck_start_int { \c_one_int }
%    \end{macrocode}
% \end{variable}^^A=<<
%
% \begin{variable}{\g_duckuments_blindduck_end_int}^^A>>=
%   Stores the paragraph with which \cs{blindduck} should end.
%    \begin{macrocode}
\int_new:N \g_duckuments_blindduck_end_int
%    \end{macrocode}
% \end{variable}^^A=<<
%^^A=<<
%
% \subsection{Constants}^^A>>=
%
% \begin{variable}{\c_duckuments_example_regex}^^A>>=
%   Regex against which the patch of \cs{includegraphics} is testing.
%    \begin{macrocode}
\regex_const:Nn \c_duckuments_example_regex
  {
     example-image-duck
    |example-image-duck.pdf
    |example-image-duck-portrait
    |example-image-duck-portrait.pdf
  }
%    \end{macrocode}
% \end{variable}^^A=<<
%
% \begin{variable}{\c_duckuments_range_regex}^^A>>=
%   Regex against which the optional range in \cs{blindduck} is checked.
%    \begin{macrocode}
\regex_const:Nn \c_duckuments_range_regex { (\d+|\d+-|-\d+|\d+-\d+|-) }
%    \end{macrocode}
% \end{variable}^^A=<<
%
% \begin{variable}{\c_duckuments_blindduck_pars_int}^^A>>=
%    \begin{macrocode}
\int_const:Nn \c_duckuments_blindduck_pars_int { 5 }
%    \end{macrocode}
% \end{variable}^^A=<<
%
% \begin{variable}{\c_duckuments_example_pages_int}^^A>>=
% Define a macro that gets the page count of a PDF (this is engine dependent):
%    \begin{macrocode}
\sys_if_engine_pdftex:T
  {
    \cs_new_protected:Npn \duckuments_set_to_pdf_page_count:Nn #1 #2
      {
        \group_begin:
        \pdfximage { #2 }
        \exp_args:NNNo
        \group_end:
        \int_set:Nn #1 { \the \pdflastximagepages }
      }
  }
\sys_if_engine_luatex:T
  {
    \cs_new_protected:Npn \duckuments_set_to_pdf_page_count:Nn #1 #2
      {
        \group_begin:
        \saveimageresource { #2 }
        \exp_args:NNNo
        \group_end:
        \int_set:Nn #1 { \lastsavedimageresourcepages }
      }
  }
\sys_if_engine_xetex:T
  {
    \cs_new_protected:Npn \duckuments_set_to_pdf_page_count:Nn #1 #2
      {
        \int_set:Nn #1 { \XeTeXpdfpagecount " #2 " }
      }
  }
\bool_lazy_any:nTF
  {
    { \sys_if_engine_luatex_p: }
    { \sys_if_engine_pdftex_p: }
    { \sys_if_engine_xetex_p: }
  }
  { \if_false: }
  { \if_true: }
  \group_begin:
  \char_set_catcode_other:N \%
  \cs_new_protected:Npn \duckuments_set_to_pdf_page_count:Nn #1 #2
    {
      \group_begin:
      \char_set_catcode_other:N \%
      \char_set_catcode_letter:N \:
      \char_set_catcode_ignore:n { 32 }
      \ior_shell_open:Nn \g_tmpa_ior { extractbb ~ -O ~ #2 }
      \ior_map_inline:Nn \g_tmpa_ior
        {
          \__duckuments_set_to_pdf_page_count_aux_a:w ##1 %%Pages: \q_stop
        }
      \ior_close:N \g_tmpa_ior
      \exp_args:NNNo
      \group_end:
      \int_set:Nn #1 { \int_use:N \l_tmpa_int }
    }
  \cs_new_protected:Npn \__duckuments_set_to_pdf_page_count_aux_a:w
    #1 %%Pages: #2 \q_stop
    {
      \tl_if_empty:nT { #1 }
        { \__duckuments_set_to_pdf_page_count_aux_b:w #2 \q_stop }
    }
  \cs_new_protected:Npn \__duckuments_set_to_pdf_page_count_aux_b:w
    #1 %%Pages: \q_stop
    {
      \int_set:Nn \l_tmpa_int { #1 }
      \ior_map_break: 
    }
  \group_end:
\fi:
%    \end{macrocode}
% Setting the constant:
%    \begin{macrocode}
\bool_if:nTF
  {
    \str_if_eq_p:Vn \c_sys_jobname_str { example-image-duck }
    || \str_if_eq_p:Vn \c_sys_jobname_str { example-image-duck-portrait }
  }
  { \int_const:Nn \c_duckuments_example_pages_int { \c_one_int } }
  {
    \group_begin:
      \duckuments_set_to_pdf_page_count:Nn \l_tmpa_int
        { example-image-duck.pdf }
      \duckuments_set_to_pdf_page_count:Nn \l_tmpb_int
        { example-image-duck-portrait.pdf }
      \int_const:Nn \c_duckuments_example_pages_int
        { \int_min:nn { \l_tmpa_int } { \l_tmpb_int } }
    \group_end:
  }
%    \end{macrocode}
% \end{variable}^^A=<<
%^^A=<<
%
% \subsection{Messages}^^A>>=
%
%    \begin{macrocode}^^A duckuments option~unknown >>=
\msg_new:nnnn { duckuments } { option~unknown }
  {
    Unknown~option~'#1'~for~package~duckuments.
  }
  { 
    \ ~__________________________________\\
    \ (Quack!~Nothing~here,~sorry.~Quack!)\\
    \ ~""""""""""""""""""""""""""""""""""\\
    \ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\string\ \\
    \ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~>()_\\
    \ \ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~(__)__
  }
%    \end{macrocode}^^A=<<
%    \begin{macrocode}^^A duckuments non-boolean~toc >>=
\msg_new:nnnn { duckuments } { non-boolean~toc }
  {
    A~non-boolean~value~`#1`~was~received~for~the~`toc`~option~during~package~
    load~time.~It~is~assumed~this~was~given~to~\string\documentclass\ and~
    therefore~ignored.
  }
  { 
    \ ~__________________________________\\
    \ (Quack!~Nothing~here,~sorry.~Quack!)\\
    \ ~""""""""""""""""""""""""""""""""""\\
    \ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\string\ \\
    \ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~>()_\\
    \ \ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~(__)__
  }
%    \end{macrocode}^^A=<<
%    \begin{macrocode}^^A duckuments out~of~range >>=
\msg_new:nnnn { duckuments } { out~of~range }
  {
    You~requested~element~#3~out~of~the~range~#1~to~#2~of~array~'#4'.\\
    I'll~just~use~element~#1~for~you.
  }
  { 
    \ ~__________________________________\\
    \ (Quack!~Nothing~here,~sorry.~Quack!)\\
    \ ~""""""""""""""""""""""""""""""""""\\
    \ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\string\ \\
    \ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~>()_\\
    \ \ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~\ ~(__)__
  }
%    \end{macrocode}^^A=<<
%
% \begin{macro}{\duckuments_patch_see_duckumentation:}^^A>>=
%    \begin{macrocode}
\cs_new:Npn \duckuments_patch_see_duckumentation:
  {%>>=
    \cs_set:Nn \msg_see_documentation_text:n
      {
        \\\\
        See~the~\str_if_eq:nnTF { ##1 } { duckuments } { duckumentation }
          {
            \str_if_eq:nnTF { ##1 } { LaTeX } { LaTeX3~ } { ##1~ }
            documentation
          }~for~further~information.
      }
  }%=<<
\duckuments_patch_see_duckumentation:
%    \end{macrocode}
% \end{macro}^^A=<<
%^^A=<<
%
% \subsection{Options and Configurations}^^A>>=
%    \begin{macrocode}
\keys_define:nn { duckuments }
  {%>>=
    ,immediate .bool_set:N = \l_duckuments_immediate_bool
    ,immediate .default:n = true
    ,full  .code:n =
      \duckuments_blindduck_range_test:n { 1-\c_duckuments_blindduck_pars_int }
    ,all   .meta:n = { full }
    ,maths .choice:
    ,maths / both    .code:n =
      {
        \bool_set_true:N \l_duckuments_math_inline_bool
        \bool_set_true:N \l_duckuments_math_display_bool
      }
    ,maths / display .code:n = \bool_set_true:N \l_duckuments_math_display_bool
    ,maths / inline  .code:n = \bool_set_true:N \l_duckuments_math_inline_bool
    ,maths / none    .code:n =
      {
        \bool_set_false:N \l_duckuments_math_inline_bool
        \bool_set_false:N \l_duckuments_math_display_bool
      }
    ,maths .default:n = both
    ,toc   .code:n =
      {
        \str_case:nnF { #1 }
          {
            { true  } { \bool_set_true:N  \l_duckuments_toc_bool }
            { false } { \bool_set_false:N \l_duckuments_toc_bool }
          }
          {
            \msg_warning:nnn { duckuments } { non-boolean~toc } { #1 }
          }
      }
    ,toc     .default:n = true
    ,unknown .code:n =
      { \msg_error:nnx { duckuments } { option~unknown } { \l_keys_key_tl } }
  }%=<<
\ProcessKeysOptions { duckuments }
\keys_define:nn { duckuments }
  {%>>=
    ,toc     .undefine:
    ,toc     .bool_set:N = \l_duckuments_toc_bool
    ,toc     .default:n = true
    ,unknown .code:n = \duckuments_blindduck_range_test:V \l_keys_key_tl
  }%=<<
\bool_if:NTF \l_duckuments_immediate_bool
  { \AtEndOfPackage { \duckuments_patch_includegraphics: } }
  { \AtBeginDocument { \duckuments_patch_includegraphics: } }
%    \end{macrocode}
%^^A=<<
%
% \subsection{Functions}^^A>>=
%
% \subsubsection{Duckument Level}^^A>>=
%
% \begin{macro}{\duckument}^^A>>=
%    \begin{macrocode}
\NewDocumentCommand \duckument { O{} }
  {%>>=
    \group_begin:
    \keys_set:nn { duckuments } { #1 }
    \bool_if:NT \l_duckuments_toc_bool { \tableofcontents }
    \cs_if_exist_use:NT \chapter
      { {\duckuments@headings@text{0}} \blindduck }
    \duckuments@headings{1} \blindduck
    \duckuments@headings{2} \blindduck
    \duckuments@headings{3} \blindduck
    \duckuments@headings{4} \blindduck
    \section {Lists}
    \duckuments_list_example:n { itemize }
    \duckuments_list_example:n { enumerate }
    \duckuments_list_example:n { description }
    \group_end:
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\blindduck}^^A>>=
%    \begin{macrocode}
\NewDocumentCommand \blindduck { O{} }
  {%>>=
    \group_begin:
    \keys_set:nn { duckuments } { #1 }
    \duckuments@blindduck@text
    \bool_if:NT \l_duckuments_blindduck_pars_bool { \par }
    \group_end:
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\ducklist}^^A>>=
%    \begin{macrocode}
\NewDocumentCommand \ducklist {s m}
  {%>>=
    \begin{#2}
      \IfBooleanTF { #1 }
        {\ducklists@content@starred}
        {
          \str_if_eq:nnTF { #2 } { description }
            \ducklists@content@starred
            \ducklists@content
        }
    \end{#2}
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
% \begin{macro}{\ducklistlist}^^A>>=
%    \begin{macrocode}
\NewDocumentCommand \ducklistlist { s m }
  {%>>=
    \IfBooleanTF { #1 }
      { \duckuments@listlist@starred { #2 } }
      {
        \str_if_eq:nnTF { #2 } { description }
          { \duckuments@listlist@starred { description } }
          { \duckuments@listlist{#2} }
      }
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckenumerate}^^A>>=
%    \begin{macrocode}
\newcommand*\duckenumerate{\ducklist{enumerate}}
%    \end{macrocode}
% \end{macro}^^A=<<
% \begin{macro}{\duckitemize}^^A>>=
%    \begin{macrocode}
\newcommand*\duckitemize{\ducklist{itemize}}
%    \end{macrocode}
% \end{macro}^^A=<<
% \begin{macro}{\duckdescription}^^A>>=
%    \begin{macrocode}
\newcommand*\duckdescription{\ducklist{description}}
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckumentsCreateExampleFiles}^^A>>=
% Create example-image-duck.tex
%    \begin{macrocode}
\newcommand*\duckumentsCreateExampleFiles
  {%>>=
    \iow_new:N \duckuments_example_file_iow
    \iow_open:Nn \duckuments_example_file_iow { example-image-duck.tex }
    \iow_now:Nn \duckuments_example_file_iow
      { \documentclass[tikz,multi]{standalone} }
    \iow_now:Nn \duckuments_example_file_iow
      { \usepackage{tikzducks} }
    \iow_now:Nn \duckuments_example_file_iow
      { \usepackage{duckuments} }
    \iow_now:Nn \duckuments_example_file_iow
      { \begin{document} }
    \iow_now:Nn \duckuments_example_file_iow
      { \duckumentsDrawRandomDucks }
    \iow_now:Nn \duckuments_example_file_iow
      { \end{document} }
    \iow_close:N \duckuments_example_file_iow
%    \end{macrocode}
% Create example-image-duck-portrait.tex
%    \begin{macrocode}
    \iow_open:Nn \duckuments_example_file_iow
      { example-image-duck-portrait.tex }
    \iow_now:Nn \duckuments_example_file_iow
      { \documentclass[tikz,multi]{standalone} }
    \iow_now:Nn \duckuments_example_file_iow
      { \usepackage{tikzducks} }
    \iow_now:Nn \duckuments_example_file_iow
      { \usepackage{duckuments} }
    \iow_now:Nn \duckuments_example_file_iow
      { \begin{document} }
    \iow_now:Nn \duckuments_example_file_iow
      { \duckumentsDrawRandomDucks* }
    \iow_now:Nn \duckuments_example_file_iow
      { \end{document} }
    \iow_close:N \duckuments_example_file_iow
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
% \begin{macro}{\duckumentsDrawRandomDucks}^^A>>=
%    \begin{macrocode}
\newcommand*\duckumentsDrawRandomDucks
  {%>>=
    \@ifstar
      {\duckumentsDrawRandomDucks@portrait}
      {\duckumentsDrawRandomDucks@landscape}%
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%^^A=<<
%
% \subsubsection{Intern}^^A>>=
%
% \begin{macro}{\duckuments@headings}^^A>>=
%    \begin{macrocode}
\newcommand*\duckuments@headings[1]
  {%>>=
    \ifcase#1\relax
      \expandafter\chapter
    \or \expandafter\section
    \or \expandafter\subsection
    \or \expandafter\subsubsection
    \or \expandafter\paragraph
    \else \expandafter\@gobble
    \fi
    {\duckuments@headings@text{#1}}
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments@headings@level}^^A>>=
%    \begin{macrocode}
\newcommand*\duckuments@headings@level[1]
  {%>>=
    (
    \ifcase#1
      chapter
    \or section
    \or subsection
    \or subsubsection
    \or paragraph
    \fi
    )
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments@ifinline}^^A>>=
%    \begin{macrocode}
\newcommand*\duckuments@ifinline[2][]
  { \bool_if:NTF \l_duckuments_math_inline_bool { #2 } { #1 } }
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments@ifdisplay}^^A>>=
%    \begin{macrocode}
\newcommand*\duckuments@ifdisplay[2][]
  { \bool_if:NTF \l_duckuments_math_display_bool { #2 } { #1 } }
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments_list_example:n}^^A>>=
%    \begin{macrocode}
\cs_new_protected_nopar:Npn \duckuments_list_example:n #1
  {%>>=
    \subsection{Example\ for\ ducks\ (#1)}
    \ducklist { #1 }
    \subsubsection{Nested\ ducks}
    \ducklistlist { #1 }
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments@enquote}^^A>>=
%    \begin{macrocode}
\NewDocumentCommand \duckuments@enquote { s +m }
  {%>>=
    \IfBooleanTF { #1 }
      {
        \cs_if_exist_use:NTF
          \enquote { * { #2 } }
          { `#2' }
      }
      {
        \cs_if_exist_use:NTF
          \enquote { { #2 } }
          {``#2''}
      }
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckumentsDrawRandomDucks@landscape}^^A>>=
%    \begin{macrocode}
\newcommand*\duckumentsDrawRandomDucks@landscape[1][\duckuments@randoms]
  {%>>=
    \foreach\x in {1,2,...,#1}
      {\duckumentsDrawRandomDucks@draw{6.47214}{4}{3.23607}{2}}
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckumentsDrawRandomDucks@portrait}^^A>>=
%    \begin{macrocode}
\newcommand*\duckumentsDrawRandomDucks@portrait[1][\duckuments@randoms]
  {%>>=
    \foreach\x in {1,2,...,#1}
      {\duckumentsDrawRandomDucks@draw{1.8541}{3}{.92705}{1.5}}
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckumentsDrawRandomDucks@draw}^^A>>=
%    \begin{macrocode}
\newcommand*\duckumentsDrawRandomDucks@draw[4]
  {%>>=
    \begin{tikzpicture}
      \draw[fill=gray!50,use~as~bounding~box] (0,0) rectangle (#1,#2);
      \draw[gray,thin] (0,0) -- (#1,#2);
      \draw[gray,thin] (0,#2) -- (#1,0);
      \draw[gray,thin] (#3,0) -- (#3,#2);
      \draw[gray,thin] (0,#4) -- (#1,#4);
      \node at (#3,#4) {\tikz\randuck;};
      \draw[black] (0,0) rectangle (#1,#2);
    \end{tikzpicture}
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments_patch_includegraphics:}^^A>>=
%    \begin{macrocode}
\cs_new_protected_nopar:Npn \duckuments_patch_includegraphics:
  {%>>=
    \@ifpackageloaded { graphicx }
      {
        \LetLtxMacro\duckuments@includegraphicsBAK\includegraphics
        \RenewDocumentCommand \includegraphics
          { >{\duckuments_starred:n}s O{} o m }
          {
            \IfValueTF { ##3 }
              { \duckuments@includegraphicsBAK##1[{##2}][{##3}]{##4} }
              {
                \regex_match:NnTF \c_duckuments_example_regex { ##4 }
                  {
                    \duckuments@includegraphicsBAK##1
                      [{page=\duckuments_random_page:,##2}]
                      { ##4 }
                  }
                  {
                    \duckuments@includegraphicsBAK##1[{##2}]{##4}
                  }
              }
          }
      }
      {}
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments_blindduck_range_test:n}^^A>>=
%    \begin{macrocode}
\cs_new_protected:Npn \duckuments_blindduck_range_test:n #1
  {%>>=
    \regex_match:NnTF \c_duckuments_range_regex { #1 }
      {
        \seq_set_split:Nnn \l_duckuments_range_seq { - } { #1 }
        \int_compare:nNnTF
          { \c_one_int } = { \seq_count:N \l_duckuments_range_seq }
          {
            \cs_set:Npn \duckuments@blindduck@text
              {
                \duckuments_blindduck_single_par:n { #1 } 
                \duckuments_blindduck_set_next_start:n { #1 }
              }
          }
          {
            \bool_set_true:N \l_duckuments_blindduck_pars_bool
            \exp_args:Nx
            \tl_if_empty:nF
              { \seq_item:Nn \l_duckuments_range_seq { \c_one_int } }
              {
                \int_gset:Nn \g_duckuments_blindduck_start_int
                  { \seq_item:Nn \l_duckuments_range_seq { \c_one_int } }
              }
            \exp_args:Nx
            \tl_if_empty:nTF { \seq_item:Nn \l_duckuments_range_seq { 2 } }
              {
                \int_gset_eq:NN
                  \g_duckuments_blindduck_end_int
                  \g_duckuments_blindduck_start_int
              }
              {
                \int_set:Nn \g_duckuments_blindduck_end_int
                  { \seq_item:Nn \l_duckuments_range_seq { 2 } }
              }
            \duckuments_blindduck_set_text:xx
              { \int_use:N \g_duckuments_blindduck_start_int }
              { \int_use:N \g_duckuments_blindduck_end_int }
          }
      }
      {
        \exp_args:NnnV
          \msg_error:nnn { duckuments } { option~unknown } \l_keys_key_tl
      }
  }%=<<
\cs_generate_variant:Nn \duckuments_blindduck_range_test:n { V }
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments_blindduck_set_text:nn}^^A>>=
%    \begin{macrocode}
\cs_new:Npn \duckuments_blindduck_set_text:nn #1 #2
  {%>>=
    \def \duckuments@blindduck@text
      {
        \int_step_function:nnnN { #1 } { \c_one_int } { #2 }
          \duckuments_blindduck_par_loop:n
        \duckuments_blindduck_set_next_start:n { #2 }
      }
  }%=<<
\cs_generate_variant:Nn \duckuments_blindduck_set_text:nn { xx }
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments_blindduck_set_next_start:n}^^A>>=
%    \begin{macrocode}
\cs_new:Npn \duckuments_blindduck_set_next_start:n #1
  {%>>=
    \int_gset:Nn \g_duckuments_blindduck_start_int
      { \int_mod:nn { #1 } { \c_duckuments_blindduck_pars_int } + \c_one_int }
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments_blindduck_single_par:n}^^A>>=
%    \begin{macrocode}
\cs_new:Npn \duckuments_blindduck_single_par:n #1
  {%>>=
    \bool_if:nTF
      {
        \int_compare_p:nNn { #1 } > { \c_duckuments_blindduck_pars_int }
        || \int_compare_p:nNn { #1 } < { \c_one_int }
      }
      {
        \msg_error:nnxxxx { duckuments } { out~of~range }
          { 1 } { \int_use:N \c_duckuments_blindduck_pars_int } { #1 }
          { blindduck~paragraphs }
        \duckuments@blindduck@text@i
      }
      {
        \use:c { duckuments@blindduck@text@ \int_to_roman:n { #1 } }
      }
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments_blindduck_par_loop:n}^^A>>=
%    \begin{macrocode}
\cs_new:Npn \duckuments_blindduck_par_loop:n #1
  {%>>=
    \duckuments_blindduck_single_par:n { #1 }
    \par
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments_starred:n}^^A>>=
%    \begin{macrocode}
\cs_new_protected:Npn \duckuments_starred:n #1
  {%>>=
    \IfBooleanTF { #1 }
      { \def\ProcessedArgument{*} }
      { \def\ProcessedArgument{} } 
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments_random_page:}^^A>>=
%    \begin{macrocode}
\cs_new:Npn \duckuments_random_page:
  { \int_rand:n { \c_duckuments_example_pages_int } }
%    \end{macrocode}
% \end{macro}^^A=<<
%
%    \begin{macrocode}
\ExplSyntaxOff
%    \end{macrocode}
%
% \begin{macro}{\duckuments@blindduck@text}^^A>>=
%    \begin{macrocode}
\newcommand*\duckuments@blindduck@text{\duckuments@blindduck@text@i}
\newcommand*\duckuments@blindduck@text@i
  {%>>=
    There once was a very smart but sadly blind duck. When it was still a small
    duckling it was renowned for its good vision. But sadly as the duck grew
    older it caught a sickness which caused its eyesight to worsen. It became so
    bad, that the duck couldn't read the notes it once took containing much of
    inline math\duckuments@ifinline{ just like its favoured equation: $d = u_c
    \cdot k$}. Only displayed equations remained legible%
    \duckuments@ifdisplay[.]{ so it could still read \begin{equation}d = r a^k
    e\hbox{.}\end{equation}} That annoyed the smart duck, as it wasn't able to
    do its research any longer. It called for its underduckling and said:
    \duckuments@enquote{Go, find me the best eye ducktor there is. He shall
    heal me from my disease!}%
  }%=<<
\newcommand*\duckuments@blindduck@text@ii
  {%>>=
    \duckuments@enquote{But my duck, how are you supposed to manage your daily
    routines without my visual guidance}, replied the underduckling. The smart
    duck's face turned grim in anger. \duckuments@enquote{You dare to talk
    back?} The underduckling blushed ashamed. How could he have objections
    after his duck gave strict orders? The underduckling was so embarrassed
    about his own behaviour he had to solve an equation.%
  }%=<<
\newcommand*\duckuments@blindduck@text@iii
  {%>>=
    After the equation was solved and the underduckling prepared his leave for
    the next day it fell asleep in a shaky mood. It did not know what the
    journey had prepared for him and if he was prepared enough for it. His sleep
    was restless. The dreams he had that night were not calm and bright as they
    used to be for an innocent underduckling.%
  }%=<<
\newcommand*\duckuments@blindduck@text@iv
  {%>>=
    Before dawn the underduckling woke. He didn't have the feeling of being well
    rested. But nonetheless he knew that this was the day he should leave.
    Except saying goodbye to his beloved ones there was nothing holding him
    back. His duck had sent him on the most important mission a five weeks old
    inexperienced underduckling was ever sent on. He bid farewell to his mother,
    all his brothers and sisters, and finally from his duck. The bag was
    shouldered, the boots were tied, the underduckling left.%
  }%=<<
\newcommand*\duckuments@blindduck@text@v
  {%>>=
    As the underduckling went along he saw a tree. It was so tall he couldn't
    even approximate its height. Oh, how small he felt. What should he, a small
    duckling whose plumage was still fluffy, achieve in this vast, gigantic
    world? He stuck his trembling wings under the straps of his backpack to calm
    his shaking limbs. Where should he start his search? How should he survive
    in the hostile nature surrounding the sheltered pond of his community?
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments@headings@text}^^A>>=
%    \begin{macrocode}
\newcommand*\duckuments@headings@text[1]
  {A friendly duck at level #1 \duckuments@headings@level{#1}}
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\ducklists@content}^^A>>=
%    \begin{macrocode}
\newcommand*\ducklists@content
  {%>>=
    \item First swims father drake
    \item Then floats mother duck
    \item After her paddles baby duckling
    \item And over there bathes uncle canard
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\ducklists@content@starred}^^A>>=
%    \begin{macrocode}
\newcommand*\ducklists@content@starred
  {%>>=
    \item[drake] is the swimming father
    \item[duck] is the floating mother
    \item[duckling] is the paddling baby
    \item[canard] is the bathing uncle
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments@listlist}^^A>>=
%    \begin{macrocode}
\newcommand*\duckuments@listlist[1]
  {%>>=
    \begin{#1}
      \item swimming father drake
        \begin{#1}
          \item swimming father drake
            \begin{#1}
              \item swimming father drake
                \begin{#1}
                  \item swimming father drake
                  \item floating mother duck
                \end{#1}
              \item floating mother duck
            \end{#1}
          \item floating mother duck
        \end{#1}
      \item floating mother duck
    \end{#1}%
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%
% \begin{macro}{\duckuments@listlist@starred}^^A>>=
%    \begin{macrocode}
\newcommand*\duckuments@listlist@starred[1]
  {%>>=
    \begin{#1}
      \item[drake] is the swimming father
        \begin{#1}
          \item[drake] is the swimming father
            \begin{#1}
              \item[drake] is the swimming father
                \begin{#1}
                  \item[drake] is the swimming father
                  \item[duck] is the floating mother
                \end{#1}
              \item[duck] is the floating mother
            \end{#1}
          \item[duck] is the floating mother
        \end{#1}
      \item[duck] is the floating mother
    \end{#1}%
  }%=<<
%    \end{macrocode}
% \end{macro}^^A=<<
%^^A=<<
%^^A=<<
%
%    \begin{macrocode}
\endinput
%    \end{macrocode}
%
% \end{implementation}^^A=<<
%
%    \begin{macrocode}