add 'DirsWithPrefix' function

goutil.go

@@ -85,6 +85,22 @@ func PathExists(path string) bool {
 	}
 }
 
+func DirsWithPrefix(path string, prefix string) ([]string, error) {
+	dirs := []string{}
+	files, err := ioutil.ReadDir(path)
+	if err != nil {
+		return dirs, err
+	}
+	for _, file := range files {
+		if file.IsDir() {
+			if name := file.Name(); strings.HasPrefix(name, prefix) {
+				dirs = append(dirs, name)
+			}
+		}
+	}
+	return dirs, nil
+}
+
 func AskFor(question string) (string, error) {
 	fmt.Print(question + ": ")
 	reader := bufio.NewReader(os.Stdin)