How to place a comma in 'a{b,c,d}e' metanotation

[Dan Bernstein]

If you want to quote the comma, quote the comma.

  % echo a{b,c,d,','}e
  abe ace ade a,e

> 	xset fp+ /path/{dir1\,,dir2\,,dir3}

  % echo /path/dir{1',',2',',3}
  /path/dir1, /path/dir2, /path/dir3

Disclaimer: This is probably portable but I don't know that it is.

---Dan