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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def ip6_address(self):
 """Returns the IPv6 address of the network interface. If multiple interfaces are provided, the address of the first found is returned. """

        if self._ip6_address is None and self.network is not None:
            self._ip6_address = self._get_ip_address(
                libvirt.VIR_IP_ADDR_TYPE_IPV6)

        return self._ip6_address