tree/tree.go
func GetAttrValOrEmpty(n Elem, local, space string) string {
	val, ok := GetAttributeVal(n, local, space)
	if !ok {
		return ""
	}
	return val
}
func GetAttrValOrEmpty(n Elem, local, space string) string {
	val, ok := GetAttributeVal(n, local, space)
	if !ok {
		return ""
	}
	return val
}
//GetAttrValOrEmpty is like GetAttributeVal, except it returns an empty string if
//the attribute is not found instead of false.