code: function Mixin_addMethod(hostClass, instanceKey, mixinMethodName, hostMethodName) {
      var method = this.prototype[mixinMethodName];
      check(method, Function);
  
      var wrappedMethod = _wrapMixinMethod.call(this, method);
  
      Object.defineProperty(hostClass.prototype, hostMethodName, {
          value: wrappedMethod,
          enumerable: false,
          configurable: false,
          writable: true
      });
  
      Mixin_setInstanceKey(hostClass, method, instanceKey);
  }
docs: Adds method of Mixin subclass to host class prototype.
  
  @private
  @param {Function} this Mixin subclass (not instance)
  @param {String} mixinMethodName name of method in Mixin subclass
  @param {String} hostMethodName (optional) name of created proxy method on host object, same if not specified
  @param {Object} hostObject object class, must be specified as the last parameter (2nd or 3rd)