code: func NetworkSetNsPid(iface *net.Interface, nspid int) error {
  	data := uint32Attr(syscall.IFLA_NET_NS_PID, uint32(nspid))
  	return networkSetNsAction(iface, data)
  }
docs: // Move a particular network interface to a particular network namespace
  // specified by PID. This is identical to running: ip link set dev $name netns $pid