code: public function getUrl($user, $hostname, $secret)
      {
          $args = func_get_args();
          $encoder = 'https://chart.googleapis.com/chart?chs=200x200&chld=M|0&cht=qr&chl=';
          $urlString = '%sotpauth://totp/%s(%s)%%3Fsecret%%3D%s'.(array_key_exists(3, $args) && !is_null($args[3]) ? ('%%26issuer%%3D'.$args[3]) : '');
          $encoderURL = sprintf($urlString, $encoder, $hostname, $user, $secret);
  
          return $encoderURL;
      }
docs: NEXT_MAJOR: Add a new parameter called $issuer.
  
  @param string $user
  @param string $hostname
  @param string $secret
  
  @return string