public static function has_slash(): 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 $a ){
      if ( (strpos($a, '/') !== false) || (strpos($a, '\\') !== false) ){
        return true;
      }
    }

    return false;
  }