code: def _is_notation(ip, notation, _isnm):
      
      notation_orig = notation
      notation = _get_notation(notation)
      if notation not in _CHECK_FUNCT_KEYS:
          raise ValueError('_is_notation: unkown notation: "%s"' % notation_orig)
      return _CHECK_FUNCT[notation][_isnm](ip)
docs: Internally used to check if an IP/netmask is in the given notation.