Creating Chorded Notes

[Eric Knapp]

Hi, all.

I'm trying to write a music function that creates chorded notes. I'm
starting simply and I'm stumped. How would I create this simple music
expression in a function?

  <a c>2

Is there a grob for these? What I'm working on is being able to
customize the individual NoteHead and Stem grobs for each note.

Thanks,

-Eric