package api import "net/http" type apiTransport struct { clientId string } var _ http.RoundTripper = (*apiTransport)(nil) // RoundTrip implements http.RoundTripper. func (a *apiTransport) RoundTrip(req *http.Request) (*http.Response, error) { req.Header.Add("Client-ID", a.clientId) return http.DefaultTransport.RoundTrip(req) }