# svmono with 'draft' causes lstlistings to produce no output

Why does the following produce no output?

\documentclass[draft]{svmono}
\usepackage{listings}
\begin{document}

\begin{lstlisting}
theorem :: GROUP_10:14
for G being finite Group,
p being prime (natural number) holds
(for H being Subgroup of G st
H is_p-group_of_prime p holds
\end{lstlisting}

\end{document}


(Obviously it is easy to fix this issue by switching off 'draft' -- but I would like to understand what is happening.)

-
It is unrelated to svmono. Class options are global options so it gets passed to listings the draft option of listings suppresses file handling as far as I can see. The listings documentation says
draft