imenu--split
imenu--split is a compiled Lisp function in `imenu.el
'.
(imenu--split LIST N)
Split LIST into sublists of max length N.
Example (imenu--split '(1 2 3 4 5 6 7 8) 3)-> '((1 2 3) (4 5 6) (7 8))
The returned list DOES NOT share structure with LIST.