def __init__(self, address, strict=True):
        """Instantiate a new IPv6 Network object.

        Args:
            address: A string or integer representing the IPv6 network or the
              IP and prefix/netmask.
              '2001:db8::/128'
              '2001:db8:0000:0000:0000:0000:0000:0000/128'
              '2001:db8::'
              are all functionally the same in IPv6.  That is to say,
              failing to provide a subnetmask will create an object with
              a mask of /128.

              Additionally, an integer can be passed, so
              IPv6Network('2001:db8::') ==
                IPv6Network(42540766411282592856903984951653826560)
              or, more generally
              IPv6Network(int(IPv6Network('2001:db8::'))) ==
                IPv6Network('2001:db8::')

            strict: A boolean. If true, ensure that we have been passed
              A true network address, eg, 2001:db8::1000/124 and not an
              IP address on a network, eg, 2001:db8::1/124.

        Raises:
            AddressValueError: If address isn't a valid IPv6 address.
            NetmaskValueError: If the netmask isn't valid for
              an IPv6 address.
            ValueError: If strict was True and a network address was not
              supplied.

        """
        _BaseNetwork.__init__(self, address)

        # Efficient constructor from integer or packed address
        if isinstance(address, (bytes, _compat_int_types)):
            self.network_address = IPv6Address(address)
            self.netmask, self._prefixlen = self._make_netmask(
                self._max_prefixlen)
            return

        if isinstance(address, tuple):
            if len(address) > 1:
                arg = address[1]
            else:
                arg = self._max_prefixlen
            self.netmask, self._prefixlen = self._make_netmask(arg)
            self.network_address = IPv6Address(address[0])
            packed = int(self.network_address)
            if packed & int(self.netmask) != packed:
                if strict:
                    raise ValueError('%s has host bits set' % self)
                else:
                    self.network_address = IPv6Address(packed &
                                                       int(self.netmask))
            return

        # Assume input argument to be string or any object representation
        # which converts into a formatted IP prefix string.
        addr = _split_optional_netmask(address)

        self.network_address = IPv6Address(self._ip_int_from_string(addr[0]))

        if len(addr) == 2:
            arg = addr[1]
        else:
            arg = self._max_prefixlen
        self.netmask, self._prefixlen = self._make_netmask(arg)

        if strict:
            if (IPv6Address(int(self.network_address) & int(self.netmask)) !=
                    self.network_address):
                raise ValueError('%s has host bits set' % self)
        self.network_address = IPv6Address(int(self.network_address) &
                                           int(self.netmask))

        if self._prefixlen == (self._max_prefixlen - 1):
            self.hosts = self.__iter__
Instantiate a new IPv6 Network object.

        Args:
            address: A string or integer representing the IPv6 network or the
              IP and prefix/netmask.
              '2001:db8::/128'
              '2001:db8:0000:0000:0000:0000:0000:0000/128'
              '2001:db8::'
              are all functionally the same in IPv6.  That is to say,
              failing to provide a subnetmask will create an object with
              a mask of /128.

              Additionally, an integer can be passed, so
              IPv6Network('2001:db8::') ==
                IPv6Network(42540766411282592856903984951653826560)
              or, more generally
              IPv6Network(int(IPv6Network('2001:db8::'))) ==
                IPv6Network('2001:db8::')

            strict: A boolean. If true, ensure that we have been passed
              A true network address, eg, 2001:db8::1000/124 and not an
              IP address on a network, eg, 2001:db8::1/124.

        Raises:
            AddressValueError: If address isn't a valid IPv6 address.
            NetmaskValueError: If the netmask isn't valid for
              an IPv6 address.
            ValueError: If strict was True and a network address was not
              supplied.

        
product/gradle-plugin/src/main/python/pip/_vendor/ipaddress.py