code: def check(self, records):
          
          for value, target in records:
              LOGGER.info("%s [%s]: %s", self.name, target, value)
              if value is None:
                  self.notify(self.no_data, value, target)
                  continue
              for rule in self.rules:
                  if self.evaluate_rule(rule, value, target):
                      self.notify(rule['level'], value, target, rule=rule)
                      break
              else:
                  self.notify('normal', value, target, rule=rule)
  
              self.history[target].append(value)
docs: Check current value.