private function strip_tags($node, $tag_names)
{
foreach ($tag_names as $tag_name) {
$elements = $node->getElementsByTagName($tag_name);
$length = $elements->length;
if (0 === $length) {
continue;
}
for ($i = $length - 1; $i >= 0; $i--) {
$element = $elements->item($i);
$parent_node = $element->parentNode;
$parent_node->removeChild($element);
if ('body' !== $parent_node->nodeName && AMP_DOM_Utils::is_node_empty($parent_node)) {
$parent_node->parentNode->removeChild($parent_node);
}
}
}
}