1package main
 2
 3import (
 4	"net/http"
 5	"time"
 6)
 7
 8func Racer(a, b string) (winner string) {
 9	aDuration := measureResponseTime(a)
10	bDuration := measureResponseTime(b)
11
12	if aDuration < bDuration {
13		return a
14	}
15	return b
16}
17
18func measureResponseTime(url string) time.Duration {
19	start := time.Now()
20	http.Get(url)
21	return time.Since(start)
22}