@classmethod
    def _make_netmask(cls, arg):
        if arg not in cls._netmask_cache:
            if isinstance(arg, _compat_int_types):
                prefixlen = arg
            else:
                prefixlen = cls._prefix_from_prefix_string(arg)
            netmask = IPv6Address(cls._ip_int_from_prefix(prefixlen))
            cls._netmask_cache[arg] = netmask, prefixlen
        return cls._netmask_cache[arg]
Return the string to use as the ``__doc__`` attribute of the property
dataset/ETHPy150Open anzev/hedwig/build/pip/pip/_vendor/ipaddress.py/_BaseV6._make_netmask--crossover with--dataset/ETHPy150Open python-openxml/python-docx/docx/oxml/xmlchemy.py/OptionalAttribute._docstring