When building a custom widget that requires a unique set of properties, you define these in the widget's ______ constructor.

When building a custom widget that requires a unique set of properties, you define these in the widget's special() constructor. The constructor of a custom widget is where you define and initialize its properties or parameters. By providing a dedicated constructor, you can enforce the required properties for the widget, ensuring that developers using your widget provide the necessary information. This enhances the widget's usability and makes its usage more explicit and self-documenting.