When you want to output values in the same order as the user give it to you e.g. when you read then write JSON or TOML files and those files can be written by a

When you want to output values in the same order as the user give it to you e.g. when you read then write JSON or TOML files and those files can be written by a real human. Changing the order feel arbitrary. When you have a language that support keyword arguments (kwargs) like Ruby or Python more recently.