tree
FilesPackage: tree
Prints an indented tree, what ls -R does less legibly. tree -L 2 caps the depth, which makes a deployment directory fit on one screen.
What its options do in the lessons
From the same glossary the lessons render under their commands, so the two cannot disagree.
tree -L- Descends only that many levels. Without the limit, the tree of a system directory scrolls past for minutes.