code: def variables(self):
          
          if self._variables is None:
              self._variables = VariableList(
                  self._version,
                  service_sid=self._solution['service_sid'],
                  environment_sid=self._solution['sid'],
              )
          return self._variables
docs: Access the variables
  
          :returns: twilio.rest.serverless.v1.service.environment.variable.VariableList
          :rtype: twilio.rest.serverless.v1.service.environment.variable.VariableList