How set html 'lang' to match node 'langcode'?

Question

I would like to change a node's html 'lang' from site's default to the node's 'langcode'.

For example, if I create a node and while creating I select French as the language, I would like the page's html 'lang' to "fr"

So far I have this:

  /** @var \Drupal\Core\Template\Attribute $html_attribute */
  $html_attribute = $variables['html_attributes'];
  $node_langcode = $node->get('langcode')->value;
  if ($html_attribute->hasAttribute("lang")) {
    $html_attribute->removeAttribute('lang');
    $html_attribute->setAttribute('lang', $node_langcode);
  }

Answer 1

This code worked properly

if(!empty($node) && $node instanceof NodeInterface) {
    /** @var \Drupal\Core\Template\Attribute $html_attribute */
    $html_attribute = $variables['html_attributes'];
    $node_langcode = $node->get('langcode')->value;
    if ($html_attribute->hasAttribute("lang")) {
      $html_attribute->removeAttribute('lang');
      $html_attribute->setAttribute('lang', $node_langcode);
    }
  }