def METHOD_NAME(
    cls, event: TCPScanEvent, target_machine: Machine
) -> NetworkServices:
    new_services: NetworkServices = {}
    for port in cls._get_open_ports(event):
        socket_address = SocketAddress(ip=event.target, port=port)
        if socket_address in target_machine.network_services:
            # The TCPScanEvent contains no information about services, so this method always
            # uses NetworkService.Unknown. If a service has already been discovered for this
            # socket address, then it should not be overwritten.
            continue
        new_services[socket_address] = NetworkService.UNKNOWN
    return new_services