A RadioGroup is used to coordinate the activity of a group of RadioButtons. It ensures that only one of the
RadioButtons is on at a time, and provides a value property which
is equal to the value of the currently selected RadioButton. It
also provides an action property which is invoked when the user
changes the selection.
You can iterate over the RadioButtons contained in a RadioGroup, which means you can use a RadioGroup directly in the place_row and place_column methods of a container.
- Action to perform when the value changes as a result of the user clicking on a radio button.