Created Empty() function for URLSet

Author: jsgm

urls.go

@@ -6,12 +6,16 @@ import (
 )
 
 func (s URLSet) First() *url.URL {
-	if len(s) == 0 {
+	if s.Empty() {
 		return nil
 	}
 	return s[0]
 }
 
+func (s URLSet) Empty() bool {
+	return len(s) == 0
+}
+
 func appendURL(target *URLSet, value string) error {
 	u, err := url.Parse(value)
 	if err != nil || u.Scheme == "" || u.Host == "" {