class['a]radiogroup :object..end
Radio group governs the set of LTerm_widget.radio objects. At each given moment of time only one
of the objects in the "on" state and the rest are in the "off" state.
method on_state_change : ?switch:LTerm_widget_callbacks.switch -> ('a option -> unit) -> uniton_state_change ?switch f calls f when the state of the group is changed.method state : 'a optionSome id with the id of "on" object
in the group or None if no objects were added to the group yet.method register_object : 'a radio -> unitmethod switch_to : 'a -> unitswitch_to id switches radio group to the state Some id, calls LTerm_widget.radio.on
method of the object with the given id and LTerm_widget.radio.off method of all other objects
added to the group.