code: func (o *Object) Attr(attr string) string {
  	o.mu.RLock()
  	defer o.mu.RUnlock()
  	if v := o.attr[attr]; len(v) > 0 {
  		return v[0]
  	}
  	return ""
  }
docs: // Attr returns the object's attribute value for the provided attr,
  // or the empty string if unset.  To distinguish between unset,
  // an empty string, or multiple attribute values, use Attrs.