\RequirePackage{listings}
\RequirePackage{xcolor}

\colorlet{punct}{white!60!black}
\colorlet{numb}{white!30!black}

\lstdefinelanguage{fuspel}{
    showstringspaces=false,
		morekeywords={code,main},
		keepspaces=true,
    literate=
     *{0}{{{\color{numb}0}}}{1}
      {1}{{{\color{numb}1}}}{1}
      {2}{{{\color{numb}2}}}{1}
      {3}{{{\color{numb}3}}}{1}
      {4}{{{\color{numb}4}}}{1}
      {5}{{{\color{numb}5}}}{1}
      {6}{{{\color{numb}6}}}{1}
      {7}{{{\color{numb}7}}}{1}
      {8}{{{\color{numb}8}}}{1}
      {9}{{{\color{numb}9}}}{1}
      {:}{{{\color{punct}{:}}}}{1}
      {;}{{{\color{punct}{;}}}}{1}
      {,}{{{\color{punct}{,}}}}{1}
      {=}{{{\color{punct}{=}}}}{1}
			{!}{{{\color{punct}{\textbf{!}}}}}{1}
			{(}{{{\color{punct}{(}}}}{1}
      {)}{{{\color{punct}{)}}}}{1}
      {[}{{{\color{punct}{[}}}}{1}
      {]}{{{\color{punct}{]}}}}{1}
}

\newcommand{\fuspel}[1]{\lstinline[language=fuspel]$#1$}