code: public function get($iSize = 150, $sECLevel = 'L', $iMargin = 1)
      {
          return self::API_URL . $iSize . 'x' . $iSize . '&cht=qr&chld=' . $sECLevel . '|' . $iMargin . '&chl=' . $this->sData;
      }
docs: Get the URL of QR Code.
  
  @param integer $iSize Default 150
  @param string $sECLevel Default L
  @param integer $iMargin Default 1
  
  @return string The API URL configure.