code: func (b *Bundle) AddTemplateDir(root string) *Bundle {
  	var err = filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
  		if err != nil {
  			return err
  		}
  		if info.IsDir() {
  			return nil
  		}
  		if !strings.HasSuffix(path, ".soy") {
  			return nil
  		}
  		b.AddTemplateFile(path)
  		return nil
  	})
  	if err != nil {
  		b.err = err
  	}
  	return b
  }
docs: // AddTemplateDir adds all *.soy files found within the given directory
  // (including sub-directories) to the bundle.