\documentclass[a4paper]{article}

\usepackage{graphics}
\begin{document}

Documents for \verb+lilypond-book+ may freely mix music and text. The music
snippets will be properly line-broken. For example,

{%
\parindent 0pt
\noindent
\ifx\preLilyPondExample \undefined
\else
  \expandafter\preLilyPondExample
\fi
\def\lilypondbook{}%
\input{c8/lily-40da36e9-systems.tex}
\ifx\postLilyPondExample \undefined
\else
  \expandafter\postLilyPondExample
\fi
}


\end{document}