* < value of #'ligature-primitive-callback of Voice.NoteHead >
*
* TODO: What we are doing here on the c++ level, should actually be
* performed on the SCM level. However, I do not know how to teach
* < value of #'ligature-primitive-callback of Voice.NoteHead >
*
* TODO: What we are doing here on the c++ level, should actually be
* performed on the SCM level. However, I do not know how to teach