text: /*
   * Copyright 2019 Google LLC.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  /**
   * Toggles the visibility of an HTML element below the button.
   * @param button clicked button element
   */
  function toggleNextSiblingVisibility(button) {
    const nextSibling = button.parentElement.nextElementSibling;
    const currentVisibility = nextSibling.style.display !== "none";
    const nextVisibility = !currentVisibility;
    nextSibling.style.display = nextVisibility ? "" : "none";
    button.innerText = nextVisibility ? "▼" : "▶";
  }
  