how to return status_code?

[mcauto]

I build this project example.

in Countries demo

curl -i -H 'Content-Type: application/json' \
    -d '{"Code":"FR","Name":"France"}' http://127.0.0.1:8080/countries
 # it has to return 201(CREATED), but return 200(OK)
curl -i -H 'Content-Type: application/json' \
    -d '{"Code":"US","Name":"United States"}' http://127.0.0.1:8080/countries
 # it has to return 201(CREATED), but return 200(OK)
curl -i -H 'Content-Type: application/json' \
    -d '{"Code":"US","Name":"United States"}' http://127.0.0.1:8080/countries
# return 209(CONFLICT) I customed
curl -i http://127.0.0.1:8080/countries/FR
curl -i http://127.0.0.1:8080/countries/US
curl -i http://127.0.0.1:8080/countries
curl -i -X DELETE http://127.0.0.1:8080/countries/FR
curl -i http://127.0.0.1:8080/countries
curl -i -X DELETE http://127.0.0.1:8080/countries/US
curl -i http://127.0.0.1:8080/countries

if data is conflict

if store[country.Code] != nil {
	rest.Error(w, "conflict", 409)
	return
}

but I don't know modified response_code override.
could you help me?