added a new iterator with error handling

Just finish the first pharse

concurrency/iterator_error_handling/main.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"time"
+
+	"github.com/davecgh/go-spew/spew"
+)
+
+type FetchResult struct {
+	Domain     string
+	StatusCode uint
+	Header     string
+}
+
+func dummyFetchUrl(url string) *FetchResult {
+	time.Sleep(time.Second * 1)
+	return &FetchResult{
+		url,
+		200,
+		"Dummy Header",
+	}
+}
+
+func main() {
+	r := dummyFetchUrl("http://www.google.com")
+	spew.Dump(r)
+}