code: def functions(self):
          
          if self._functions is None:
              self._functions = FunctionList(self._version, service_sid=self._solution['sid'], )
          return self._functions
docs: Access the functions
  
          :returns: twilio.rest.serverless.v1.service.function.FunctionList
          :rtype: twilio.rest.serverless.v1.service.function.FunctionList