-If the optional argument PREFIX is supplied, only commands which
-start with that sequence of keys are described.
-If the second argument (prefix arg, interactively) is non-null
-then only the mouse bindings are displayed."
+If optional first argument PREFIX is supplied, only commands
+which start with that sequence of keys are described.
+If optional second argument MOUSE-ONLY-P (prefix arg, interactively)
+is non-nil then only the mouse bindings are displayed."