The PO file format is part of the gettext internationalization and localization system that's commonly used in Unix-like systems. This system includes tools to ease the translation work.
This recipe demonstrates how to use these tools to help translate our add-on modules. We want to use it on a custom module, so the my_library we created in Chapter 4, Creating Odoo Add-On Modules, is a good candidate. However, feel free to replace it with some other custom module you have at hand, replacing the recipe's my_library references as appropriate.