code: def check_ntp_status(self, ntp_status_int):
          
          # convert the ntp_status integer value in a human readable value
          ntp_status_string = self.ntp_status.get(ntp_status_int, "unknown")
  
          if ntp_status_string == "unknown":
              return unknown, ("NTP status: " + ntp_status_string)
  
          # the ntp status should be synchronized (new MIB) or normalOperation (old mib)
          elif ntp_status_string != "synchronized" and ntp_status_string != "normalOperationPPS":
              # that is a critical condition, because the time reference will not be reliable anymore
              return critical, ("NTP status: " + ntp_status_string)
  
          return None
docs: check the NTP status