public function getHeaders( $source, $continue = true )
  {
    if ( false !== ( $separator_pos = strpos( $source, "\r\n\r\n" ) ) )
    {
      if ( $continue && false !== strpos( $source, 'HTTP/1.1 100 Continue' ) )
      {
        $source = trim( substr( $source, $separator_pos + 4 ) );
        $source = $this->getHeaders( $source, false );
      }
      else
      {
        $source = trim( substr( $source, 0, $separator_pos ) );
      }

      return $source;
    }

    return '';
  }