code: function deepCopyPublic(value) {
    if (typeof value === 'undefined') {
      return value;
    }
  
    const skipPrivateKeys = (key, value) => (key.startsWith('_') ? 0 : value);
  
    return window.JSON.parse(window.JSON.stringify(value, skipPrivateKeys));
  }
docs: Deep-copies the value using JSON. Underscored (private) keys are removed.
  @param {*} value Some nested value from the plotDiv object.
  @returns {*} A deepcopy of the value.