/**
* Check recursively to find the number of children in $e with tag $child_tag
* return number of qualified children
*/
public static function count_children_by_tag($e, $tag)
{
$num = 0;
foreach ($e->children() as $child) {
if ($child->tag == $tag) {
$num++;
} else {
$num += BasicChecks::count_children_by_tag($child, $tag);
}
}
return $num;
}
