public static function roots() {
    $instance = new static;

    return $instance->newQuery()
                    ->whereNull($instance->getParentColumnName())
                    ->orderBy($instance->getQualifiedOrderColumnName());
  }
public static function roots() {
    $instance = new static;

    return $instance->newQuery()
                    ->whereNull($instance->getParentColumnName())
                    ->orderBy($instance->getQualifiedOrderColumnName());
  }
public static function roots ( ) { $ instance = new static ; return $ instance -> newQuery ( ) -> whereNull ( $ instance -> getParentColumnName ( ) ) -> orderBy ( $ instance -> getQualifiedOrderColumnName ( ) ) ; }
Static query scope. Returns a query scope with all root nodes.

@return \Illuminate\Database\Query\Builder
Static query scope . Returns a query scope with all root nodes .