(let ((m (ly:make-bare-music (cdr (assoc 'internal-class-name props)) props)))
(define (set-props mus-props)
(if (and (not (null? mus-props))
(let ((m (ly:make-bare-music (cdr (assoc 'internal-class-name props)) props)))
(define (set-props mus-props)
(if (and (not (null? mus-props))