#(define (define-grob-property symbol type? description)
(if (not (equal? (object-property symbol 'backend-doc) #f))
(ly:error (_ "symbol ~S redefined") symbol))
(set-object-property! symbol 'backend-type? type?)
(set-object-property! symbol 'backend-doc description)
symbol)
#(define-grob-property 'buddies list? "List of grobs")
{ \override StaffSymbol #'buddies = #'(clef note-head) a }