'Expand a shortened IPv6 address.
Args:
ip_str: A string, the IPv6 address.
Returns:
A string, the expanded IPv6 address.'

def _explode_shorthand_ip_string(self):

    if isinstance(self, IPv6Network):
        ip_str = str(self.network_address)
    elif isinstance(self, IPv6Interface):
        ip_str = str(self.ip)
    else:
        ip_str = str(self)
    ip_int = self._ip_int_from_string(ip_str)
    parts = []
    for i in range(self._HEXTET_COUNT):
        parts.append(('%04x' % (ip_int & 65535)))
        ip_int >>= 16
    parts.reverse()
    if isinstance(self, (_BaseNetwork, IPv6Interface)):
        return ('%s/%d' % (':'.join(parts), self.prefixlen))
    return ':'.join(parts)
