code: def ipfix():
      
      if not hasattr(ipfix, 'ipflist'):
          ilist = []
          try:
              data = requests.get('http://www.iana.org/assignments/ipfix/ipfix-'
                                  'information-elements.csv')
          except requests.exceptions.RequestException:
              return []
  
          for line in data.iter_lines():
              if line:
                  line = line.decode("utf-8")
                  if re.match(r'^\d+(,[a-zA-Z0-9]+){2},', line):
                      vals = line.split(',')
                      if vals[1]:
                          ilist.append(vals[1])
  
          ipfix.ipflist = ilist
      return ipfix.ipflist
docs: Return a list of values from the list of IANA IP Flow Information Export
      (IPFIX) Entities, or an empty list if the IANA website is unreachable.
      Store it as a function attribute so that we only build the list once.