extensions/amp-story/1.0/amp-story-system-layer.js
/**
   * Reacts to the bookend state updates and updates the UI accordingly.
   * @param {boolean} isActive
   * @private
   */
Reacts to the bookend state updates and updates the UI accordingly.
@param {boolean} isActive
@private
Reacts to the bookend state updates and updates the UI accordingly . @param { boolean } isActive @private
onBookendStateUpdate_(isActive) {
    this.getShadowRoot().classList.toggle(
      'i-amphtml-story-bookend-active',
      isActive
    );
  }
onBookendStateUpdate_ ( isActive ) { this . getShadowRoot ( ) . classList . toggle ( 'i-amphtml-story-bookend-active' , isActive ) ; }
Reacts to the bookend state updates and updates the UI accordingly.
Reacts to the bookend state updates and updates the UI accordingly .