Sets the flag if traceroute result is successful or not.

def set_is_success(self, last_hop):
        """Sets the flag if traceroute result is successful or not."""
        for packet in last_hop.packets:
            if packet.rtt and not packet.is_error:
                self.is_success = True
                break
        else:
            self.set_last_hop_errors(last_hop)