public static function check_filename(): bool
  {

    $args = \func_get_args();
    // Each argument must be a string starting with a letter, and having than one character made of letters, numbers and underscores
    foreach ( $args as $a ){
      if ( !\is_string($a) || (strpos($a, '/') !== false) || (strpos($a, '\\') !== false) ){
        return false;
      }
    }
    return true;
  }