function cacheItem(contains) {
    if (!isHTMLElement(el)) {
      return;
    }
    const slotName = el.getAttribute('slot');
    if (slotName) {
      // eslint-disable-next-line no-param-reassign
      cache[slotName] = cache[slotName] || [];
      cache[slotName].push({ element: el, deepContains: contains });
    }
  }
@description Cache an html element and its `deepContains` status
@param {boolean} contains The `deepContains` status for the element
@returns {void}