Predict gender from names in Go with net/http

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
	"strconv"
	"time"
)

type Prediction struct {
	ResultStatus string  `json:"result_status"`
	Gender       *string `json:"gender"`
	Confidence   float64 `json:"confidence"`
	Source       string  `json:"source"`
	Country      string  `json:"country"`
	Reason       string  `json:"reason"`
}

var client = &http.Client{Timeout: 10 * time.Second}

func predict(name, country string) (*Prediction, error) {
	body, _ := json.Marshal(map[string]string{"name": name, "country": country})
	for attempt := 0; attempt < 3; attempt++ {
		req, _ := http.NewRequest(http.MethodPost, "https://api.finowl.co/v1/gender/name", bytes.NewReader(body))
		req.Header.Set("Authorization", "Bearer "+os.Getenv("FINOWL_API_KEY"))
		req.Header.Set("Content-Type", "application/json")
		resp, err := client.Do(req)
		if err != nil {
			return nil, err
		}
		var out struct {
			Data  *Prediction
			Error struct{ Code string }
		}
		_ = json.NewDecoder(resp.Body).Decode(&out)
		resp.Body.Close()
		switch {
		case resp.StatusCode == http.StatusOK:
			return out.Data, nil
		case resp.StatusCode == http.StatusBadRequest, resp.StatusCode == http.StatusUnauthorized:
			return nil, fmt.Errorf("request rejected (%d): %s", resp.StatusCode, out.Error.Code)
		case resp.StatusCode == http.StatusTooManyRequests && out.Error.Code == "rate_limited":
			secs, _ := strconv.Atoi(resp.Header.Get("Retry-After"))
			time.Sleep(time.Duration(max(secs, 1)) * time.Second)
		default:
			return nil, fmt.Errorf("finowl error %d: %s", resp.StatusCode, out.Error.Code)
		}
	}
	return nil, fmt.Errorf("still rate limited")
}

func main() {
	for _, in := range [][2]string{{"Andrea", "IT"}, {"Andrea", "US"}, {"Qwzx", "GB"}} {
		p, err := predict(in[0], in[1])
		if err != nil {
			log.Fatal(err)
		}
		if p.ResultStatus == "unknown" {
			fmt.Printf("%s [%s]: unknown, reason=%s\n", in[0], in[1], p.Reason)
			continue
		}
		fmt.Printf("%s [%s]: %s confidence=%.2f source=%s country=%s\n", in[0], in[1], *p.Gender, p.Confidence, p.Source, p.Country)
	}
}