(note-heads ,ly:grob-array? "List of note head grobs")
(note-head ,ly:grob? "A single note head")
(right-items ,ly:grob-array? "")
(note-heads ,ly:grob-array? "List of note head grobs")
(note-head ,ly:grob? "A single note head")
(right-items ,ly:grob-array? "")