diff -r aec7073d4645 -r daf404920ab9 ProgTutorial/document/root.tex
--- a/ProgTutorial/document/root.tex	Fri Jun 03 15:15:17 2016 +0100
+++ b/ProgTutorial/document/root.tex	Tue May 14 11:10:53 2019 +0200
@@ -105,6 +105,9 @@
 \renewcommand{\isataggrayML}{\begin{vanishML}\begin{graybox}}
 \renewcommand{\endisataggrayML}{\end{graybox}\end{vanishML}}
 
+\isakeeptag{linenosgrayML}
+\renewcommand{\isataglinenosgrayML}{\begin{vanishML}\begin{graybox}\begin{linenos}}
+\renewcommand{\endisataglinenosgrayML}{\end{linenos}\end{graybox}\end{vanishML}}
 
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 % for code that has line numbers