docs: function Director () {
      if (Director._instance) {
          throw new Error('Director instance already exists')
      }
  
      this.sceneStack = []
      this.window   = parent.window
      this.document = this.window.document
  
      // Prevent writing to some properties
      util.makeReadonly(this, 'canvas context sceneStack winSize isReady document window container isTouchScreen isMobile'.w)
  }