def _ip_int_from_prefix(self, prefixlen=None):
        if not prefixlen and prefixlen != 0:
            prefixlen = self._prefixlen
        return self._ALL_ONES ^ (self._ALL_ONES >> prefixlen)
Turn the prefix length netmask into a int for comparison.
dataset/ETHPy150Open anandology/pyjamas/pyjs/src/pyjs/lib/ipaddr.py/_BaseNet._ip_int_from_prefix