code: def _is_non_public_numeric_address(host):
      
      # for numeric hostnames, skip RFC1918 addresses, since no Tor exit
      # node will be able to reach those. Likewise ignore IPv6 addresses.
      try:
          a = ipaddress.ip_address(six.text_type(host))
      except ValueError:
          return False        # non-numeric, let Tor try it
      if a.is_loopback or a.is_multicast or a.is_private or a.is_reserved \
         or a.is_unspecified:
          return True         # too weird, don't connect
      return False
docs: returns True if 'host' is not public