+ (if (memq 'event-chord (ly:music-property arg 'types))
+ ; arg is an EventChord -> set the parenthesize property on all child notes and rests
+ (map
+ (lambda (ev)
+ (if (or (memq 'note-event (ly:music-property ev 'types))
+ (memq 'rest-event (ly:music-property ev 'types)))
+ (set! (ly:music-property ev 'parenthesize) #t)))
+ (ly:music-property arg 'elements))
+ ; No chord, simply set property for this expression:
+ (set! (ly:music-property arg 'parenthesize) #t))