\section{this is a heading}

but this is not because it spans multiple lines

\begin{figure}
\begin{center}
\begin{verbatim}so this
is
a pre
\end{verbatim}\caption{untitled}
\end{center}
\end{figure}
\subsection{heading}

text text text text text

bla bla

bla

\section{heading}

bla

\section{heading}

bla