code: function initializeAll() {
      var elements = Array.from(document.querySelectorAll('[' + Settings.Attribute.TRIGGER + ']'));
  
      var singleInstances = [];
      var groupInstances = [];
      var groupIds = [];
  
      elements.forEach(function (item) {
        var groupId = item.getAttribute(Settings.Attribute.GROUP);
        if (groupId) {
          if (!groupIds.includes(groupId)) {
            var group = elements.filter(function (el) {
              return el.getAttribute(Settings.Attribute.GROUP) === groupId;
            });
            var isAnimated = group.some(function (el) {
              return el.hasAttribute(Settings.Attribute.ANIMATED);
            });
            groupInstances.push(isAnimated ? new ExpandableAccordion(group) : new ExpandableGroup(group));
            groupIds.push(groupId);
          }
        } else {
          singleInstances.push(new ExpandableItem(item.getAttribute(Settings.Attribute.TRIGGER)));
        }
      });
  
      return singleInstances.concat(groupInstances);
    }
docs: Instantiates all instances of the expandable. Groups are instantiated separate from
  Expandables and require different parameters. This helper chunks out and groups the
  grouped expandables before instantiating all of them.
  
  @return {Array.<ExpandableItem|ExpandableGroup|ExpandableAccordion>} all instances of both types.
  @public