docs: def _parse_varnishadm(self, output, tags):
          """ Parse out service checks from varnishadm.
  
          Example output:
  
              Backend b0 is Sick
              Current states  good:  2 threshold:  3 window:  5
              Average responsetime of good probes: 0.000000
              Oldest                                                    Newest
              ================================================================
              -------------------------------------------------------------444 Good IPv4
              -------------------------------------------------------------XXX Good Xmit
              -------------------------------------------------------------RRR Good Recv
              ----------------------------------------------------------HHH--- Happy
              Backend b1 is Sick
              Current states  good:  2 threshold:  3 window:  5
              Average responsetime of good probes: 0.000000
              Oldest                                                    Newest
              ================================================================
              ----------------------------------------------------------HHH--- Happy
  
          Example output (new output format):
  
              Backend name                   Admin      Probe
              boot.default                   probe      Healthy (no probe)
              boot.backend2                  probe      Healthy 4/4
                Current states  good:  4 threshold:  3 window:  4
                Average response time of good probes: 0.002504
                Oldest ================================================== Newest
                --------------------------------------------------------------44 Good IPv4
                --------------------------------------------------------------XX Good Xmit
                --------------------------------------------------------------RR Good Recv
                ------------------------------------------------------------HHHH Happy
  
          """
          # Process status by backend.
          backends_by_status = defaultdict(list)
          for line in output.split("\n"):
              backend, status, message = None, None, None
              # split string and remove all empty fields
              tokens = filter(None, line.strip().split(' '))
              tokens = [t for t in tokens]
              if len(tokens):
                  if tokens == ['Backend', 'name', 'Admin', 'Probe']:
                      # skip the column headers that exist in new output format
                      continue
                  # parse new output format
                  # the backend name will include the vcl name
                  # so split on first . to remove prefix
                  elif len(tokens) >= 4 and tokens[1] in ['healthy', 'sick']:
                      # If the backend health was overriden, lets grab the
                      # overriden value instead of the probed health
                      backend = tokens[0].split('.', 1)[-1]
                      status = tokens[1].lower()
                  elif len(tokens) >= 4 and tokens[1] == 'probe':
                      backend = tokens[0].split('.', 1)[-1]
                      status = tokens[2].lower()
                  # Parse older Varnish backend output
                  elif tokens[0] == 'Backend':
                      backend = tokens[1]
                      status = tokens[-1].lower()
  
                  if tokens[0] == 'Current' and backend is not None:
                      try:
                          message = ' '.join(tokens[2:]).strip()
                      except Exception:
                          # If we can't parse a message still send a status.
                          self.log.exception('Error when parsing message from varnishadm')
                          message = ''
  
                  if backend is not None:
                      backends_by_status[status].append((backend, message))
  
          for status, backends in iteritems(backends_by_status):
              check_status = BackendStatus.to_check_status(status)
              for backend, message in backends:
                  service_checks_tags = ['backend:%s' % backend] + tags
                  self.service_check(self.SERVICE_CHECK_NAME, check_status, tags=service_checks_tags, message=message)