(defun no-voice-crossing ;<== Note that this version uses keys instead of simple arguments.

; This should be used like: 
; (no-voice-crossing :voices <arg> :input-mode <arg> :gracenotes? <arg> :rule-type <arg> :weight <arg>
 
).
    (&key (voices 0)  ;<== the second argument is always the initial values and should be placed in :initvals for OM
       (input-mode :all) ; options: :all, :beat, :1st-beat, :1st-voice  ;<== These options should be placed in the :menuins for OM
       (gracenotes? :include-gracenotes) ; options: :include-gracenotes, :exclude-gracenotes  <== should be removed - no gracenotes in OM
       (rule-type :true/false) ; options: :true/false :heur-switch ;<== These options should be placed in the :menuins for OM
       (weight 1)) ;<== the second argument -> :menuins
  "Voices should not cross, i.e., the pitch of simultaneous note pairs in voices are always sorted in decreasing order.

Arguments are inherited from r-pitch-pitch." ;<== should be placed in :doc for OM

  (let ((sorted-voices (sort voices #'<))) ;<== LISP code
    (mappend #'(lambda (voice1 voice2)
		 (ce::r-pitch-pitch #'(lambda (pitches) ;<== Included ce:: prefix here
				    ;; no rests -- no NILs
				    (apply #'>= (remove NIL pitches))) 
				(list voice1 voice2)
				'(0)
				input-mode
				gracenotes?
				:pitch
				rule-type weight))
	     (butlast sorted-voices)
	     (rest sorted-voices))))