- "Process all nodes of MUSIC (including MUSIC) in the DFS order.
-Apply FUNCTION on each of the nodes.
-If FUNCTION applied on a node returns true, don't process the node's subtree."
+ "Process all nodes of @var{music} (including @var{music}) in the DFS order.
+Apply @var{function} on each of the nodes. If @var{function} applied on a
+node returns @code{#t}, don't process the node's subtree.
+
+If a non-boolean is returned, it is considered the material to recurse."