'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.'

def __init__(self, address, strict=True):

    _BaseNetwork.__init__(self, 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((u'%s    has    host    bits    set' % self))
            else:
                self.network_address = IPv6Address((packed & int(self.netmask)))
        return
    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((u'%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__
