docs: 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);
  }