collectUsefulNodes = (node, usefulNodes) => {
  for (const child of node.children) {
    if (child.type === 'element') {
      if (child.attributes.id != null || child.name === 'style') {
        usefulNodes.push(child);
      } else {
        collectUsefulNodes(child, usefulNodes);
      }
    }
  }
}
@param {import('../lib/types.js').XastElement} node
@param {import('../lib/types.js').XastElement[]} usefulNodes