code: def _proxy_bypass_macosx_sysconf(host, proxy_settings):
      
      from fnmatch import fnmatch
  
      hostonly, port = splitport(host)
  
      def ip2num(ipAddr):
          parts = ipAddr.split('.')
          parts = list(map(int, parts))
          if len(parts) != 4:
              parts = (parts + [0, 0, 0, 0])[:4]
          return (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8) | parts[3]
  
      # Check for simple host names:
      if '.' not in host:
          if proxy_settings['exclude_simple']:
              return True
  
      hostIP = None
  
      for value in proxy_settings.get('exceptions', ()):
          # Items in the list are strings like these: *.local, 169.254/16
          if not value: continue
  
          m = re.match(r"(\d+(?:\.\d+)*)(/\d+)?", value)
          if m is not None:
              if hostIP is None:
                  try:
                      hostIP = socket.gethostbyname(hostonly)
                      hostIP = ip2num(hostIP)
                  except socket.error:
                      continue
  
              base = ip2num(m.group(1))
              mask = m.group(2)
              if mask is None:
                  mask = 8 * (m.group(1).count('.') + 1)
              else:
                  mask = int(mask[1:])
              mask = 32 - mask
  
              if (hostIP >> mask) == (base >> mask):
                  return True
  
          elif fnmatch(host, value):
              return True
  
      return False
docs: Return True iff this host shouldn't be accessed using a proxy
  
      This function uses the MacOSX framework SystemConfiguration
      to fetch the proxy information.
  
      proxy_settings come from _scproxy._get_proxy_settings or get mocked ie:
      { 'exclude_simple': bool,
        'exceptions': ['foo.bar', '*.bar.com', '127.0.0.1', '10.1', '10.0/16']
      }