typed.go
func (t Typed) InterfaceOr(key string, d interface{}) interface{} {
	if value, exists := t.InterfaceIf(key); exists {
		return value
	}
	return d
}
func (t Typed) InterfaceOr(key string, d interface{}) interface{} {
	if value, exists := t.InterfaceIf(key); exists {
		return value
	}
	return d
}
// Returns a string at the key, or the specified
// value if it doesn't exist or isn't a strin