code: def client_auth(self):
          
          if not self._client_auth:
              self._client_auth = E.Element('merchantAuthentication')
              E.SubElement(self._client_auth, 'name').text = self.config.login_id
              E.SubElement(self._client_auth, 'transactionKey').text = self.config.transaction_key
          return self._client_auth
docs: Generate an XML element with client auth data populated.