+## lesson-check : validate lesson Markdown.
+lesson-check : lesson-fixme
+ @bin/lesson_check.py -s . -p ${PARSER} -r _includes/links.md
+
+## lesson-check-all : validate lesson Markdown, checking line lengths and trailing whitespace.
+lesson-check-all :
+ @bin/lesson_check.py -s . -p ${PARSER} -r _includes/links.md -l -w --permissive
+
+## unittest : run unit tests on checking tools.