1. https://www.shellcheck.net/
+Cleanups
+--------
+
+o lib.sh brings in defer.sh (by way of ../lib.sh) by default. Consider
+ making use of the defer primitive to schedule automatic cleanups. This
+ makes it harder to forget to remove a temporary netdevice, kill a running
+ process or perform other cleanup when the test script is interrupted.
+
+o When adding a helper that dirties the environment, but schedules all
+ necessary cleanups through defer, consider prefixing it adf_ for
+ consistency with lib.sh and ../lib.sh helpers. This serves as an
+ immediately visible bit of documentation about the helper API.
+
+o Definitely do the above for any new code in lib.sh, if practical.
+
Customization
=============