docs: def get_config_tbk(self, confirmation_url):
          '''
          Returns a string with the ``TBK_CONFIG.dat``.
  
          :param confirmation_url: URL where callback is made.
          '''
          config = (
              "IDCOMERCIO = {commerce_id}\n"
              "MEDCOM = 1\n"
              "TBK_KEY_ID = 101\n"
              "PARAMVERIFCOM = 1\n"
              "URLCGICOM = {confirmation_path}\n"
              "SERVERCOM = {confirmation_host}\n"
              "PORTCOM = {confirmation_port}\n"
              "WHITELISTCOM = ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz 0123456789./:=&?_\n"
              "HOST = {confirmation_host}\n"
              "WPORT = {confirmation_port}\n"
              "URLCGITRA = /filtroUnificado/bp_revision.cgi\n"
              "URLCGIMEDTRA = /filtroUnificado/bp_validacion.cgi\n"
              "SERVERTRA = {webpay_server}\n"
              "PORTTRA = {webpay_port}\n"
              "PREFIJO_CONF_TR = HTML_\n"
              "HTML_TR_NORMAL = http://127.0.0.1/notify\n"
          )
          confirmation_uri = six.moves.urllib.parse.urlparse(confirmation_url)
          webpay_server = "https://certificacion.webpay.cl" if self.testing else "https://webpay.transbank.cl"
          webpay_port = 6443 if self.testing else 443
          return config.format(commerce_id=self.id,
                               confirmation_path=confirmation_uri.path,
                               confirmation_host=confirmation_uri.hostname,
                               confirmation_port=confirmation_uri.port,
                               webpay_port=webpay_port,
                               webpay_server=webpay_server)