message: adding 'once' to mixin methods
diff: @@ -114,7 +114,7 @@ define(["Tone/core/Tone"], function (Tone) {
  * @returns {Tone.Emitter}
  */
  Tone.Emitter.mixin = function(object){
  - var functions = ["on", "off", "emit"];
  + var functions = ["on", "once", "off", "emit"];
  object._events = {};
  for (var i = 0; i < functions.length; i++){
  var func = functions[i];
  