main.go

package main

import "sync"

func main() {
	var wg sync.WaitGroup

	urls := []string{"http://foo.com", "http://bar.com"}
	for _, url := range urls {
		wg.Add(1)
		defer wg.Done()
		go func(u string) {
			err := fetchData(url)
			if err != nil {
				return err
			}
		}(url)

	}
	wg.Wait()
}