Remove empty line in assert example string literal

chapters/lexicalstructure.tex

@@ -229,8 +229,7 @@ \subsection{Strings}\label{strings}
 contains (non-printable) newline characters:
 \begin{lstlisting}[language=modelica]
 assert(noEvent(length > s_small),
-       "
-The distance between the origin of frame_a and the origin of frame_b
+"The distance between the origin of frame_a and the origin of frame_b
 of a LineForceWithMass component became smaller as parameter s_small
 (= a small number, defined in the
 \"Advanced\" menu). The distance is