ArrayMax Ugen metdadata for Overtone

gistfile1.clj

;;; This is the metadata used to define the ArrayMax ugen spec.
{:name "ArrayMax",                                                                                                                                                                                                                                                           
 :summary "detect the largest value (and its position) in an array of UGens",                                                                                                                                                                                                         
 :args                                                                                                                                                                                                                                                                       
 [{:name "array", :mode :append-sequence :doc "input ugens (channelArray)"}],                                                                                                                                                                                                
 :rates #{:ar :kr},                                                                                                                                                                                                                                                          
 :doc "Finds the maximum value in an Array of UGens, and outputs the value and the index. This is for use in a SynthDef. If you simply need to find out which is the maximum in an array of numbers, use the link::Overviews/Methods#maxIndex#maxIndex:: and/or link::Overviews/M\
ethods#maxItem#maxItem:: methods defined for any Collection."}

;;; This is the example form the scdoc for Help file
;; (
;; x = {
;; 	// A collection of different tones:
;;	var son = SinOsc.ar((100, 100.3 .. 110));
;;	var val = ArrayMax.ar(son).at(0);
;;	val = LeakDC.ar(val); // the operation tends to induce DC offset
;;	Pan2.ar(val)
;; }.play
;; )
;; x.free

;;; This is my translation to Overtone
(defsynth help-array-max []                                                                                                                                                                                                                                                     
  (let [snd (sin-osc (range 100 110 0.3))                                                                                                                                                                                                                                                 
        val (select (array-max snd))                                                                                                                                                                                                                                            
        val (leak-dc val)]                                                                                                                                                                                                                                                      
    (out 0 (pan2 val))))

;; The synthdef succeeds, but cannot be instantiated.
(help-array-max) ; This crashes the scsynth