function convert($string)
 {
     if (!$this->started) {
         $this->started = true;
         $string = Utf8::instance()->trim($string);
         return $this->encoding_converter->convert($string);
     } else {
         return $this->encoding_converter->convert($string);
     }
     return $string;
 }
 /**
  * Returns the Utf8 encoding.
  * 
  * @return Utf8
  */
 public static function utf8()
 {
     return Utf8::instance();
 }