/**
* @param null $scope
* @return Terms
*/
public static function retrieveRoot($scope = null)
{
$root = new \Terms();
$root = $root->findRoot($scope);
if (!$root) {
$root = new \Terms();
$root->scope = $scope;
$root->taxonomy = $scope;
$root->name = 'Root of ' . $scope;
$root->makeRoot();
$root->save();
}
return $root;
}