code: def ipfix(instance):
      
      ipf_pattern = re.compile(r'^[a-z][a-zA-Z0-9]+')
      for key, obj in instance['objects'].items():
          if ('type' in obj and obj['type'] == 'network-traffic' and
                  'ipfix' in obj):
              for ipf in obj['ipfix']:
                  if enums.ipfix():
                      if ipf not in enums.ipfix():
                          yield JSONError("The 'ipfix' property of object "
                                          "'%s' contains a key ('%s') not in "
                                          "IANA IP Flow Information Export "
                                          "(IPFIX) Entities Registry."
                                          % (key, ipf), instance['id'],
                                          'ipfix')
                  else:
                      info("Can't reach IANA website; using regex for ipfix.")
                      if not ipf_pattern.match(ipf):
                          yield JSONError("The 'ipfix' property of object "
                                          "'%s' contains a key ('%s') not in "
                                          "IANA IP Flow Information Export "
                                          "(IPFIX) Entities Registry."
                                          % (key, ipf), instance['id'],
                                          'ipfix')
docs: Ensure the 'ipfix' property of network-traffic objects contains only
      values from the IANA IP Flow Information Export (IPFIX) Entities Registry.