code: def fetch(self):
          
          params = values.of({})
  
          payload = self._version.fetch(
              'GET',
              self._uri,
              params=params,
          )
  
          return AuthRegistrationsCredentialListMappingInstance(
              self._version,
              payload,
              account_sid=self._solution['account_sid'],
              domain_sid=self._solution['domain_sid'],
              sid=self._solution['sid'],
          )
docs: Fetch a AuthRegistrationsCredentialListMappingInstance
  
          :returns: Fetched AuthRegistrationsCredentialListMappingInstance
          :rtype: twilio.rest.api.v2010.account.sip.domain.auth_types.auth_registrations_mapping.auth_registrations_credential_list_mapping.AuthRegistrationsCredentialListMappingInstance