__HEADER__(Package for emphasizing vocabulary)
%%Provides a \vocab<[name in index]>{vocabulary} command to print vocabulary in bold blue and automatically index it.

\RequirePackage{xkeyval}

__LANGUAGE_OPTIONS__
__NEW_IF__(index,false)

\DeclareOption{index}{__SET_IF__(index,true)}
\DeclareOption{noindex}{__SET_IF__(index,false)}

__END_OPTIONS_X__

%%%%Management of vocabulary and corresponding index
\RequirePackage{xparse}
\RequirePackage{xcolor}
__IF__(index)
    \RequirePackage{imakeidx}
    \makeindex[name=vocabindex, columns=2, title=__IF__(english) Index\else Stichwortverzeichnis\fi, intoc]

    %Emphasize \vocabulary
    \RequirePackage{expl3}
    \ExplSyntaxOn
    \NewDocumentCommand{\vocab}{O{} m}{
        \textbf{\color{blue} #2}%
        \if\relax\detokenize{#1}\relax%
        \index[vocabindex]{\text_titlecase_first:n{#2}} % true branch: #1 was empty
        \else
        \index[vocabindex]{#1} % false branch: #1 was supplied
        \fi
    }
    \ExplSyntaxOff
    \newcommand\printvocabindex{
        \printindex[vocabindex]
    }
\else
    \NewDocumentCommand{\vocab}{O{} m }{
        \textbf{\color{blue} #2}
    }
\fi