diff -r 0e591f806290 -r 8a34b2ebc8cc testing1/collatz_test.sh
--- a/testing1/collatz_test.sh	Tue Dec 03 11:07:09 2019 +0000
+++ b/testing1/collatz_test.sh	Mon Jan 27 10:18:13 2020 +0000
@@ -27,7 +27,7 @@
 # purity test
 
 function scala_vars {
-   (egrep '\bvar\b|\breturn\b|\.par|ListBuffer|mutable|new Array' "$1" 2> /dev/null 1> /dev/null)
+   (egrep '\bvar\b|\breturn\b|\.par|ListBuffer|collection.mutable|util.control|new Array' "$1" 2> /dev/null 1> /dev/null)
 }