:- module switch_scope.
:- interface.

:- import_module bool.
:- import_module pair.

:- type index
    --->    first
    ;       second.

:- pred clear(index::in, pair(bool)::in, pair(bool)::out) is semidet.

:- implementation.

clear(I, P0, P) :-
    require_complete_switch [Index]
    (
        I = first,
        P0 = yes - Y,
        P = no - Y
    ;
        I = second,
        P0 = X - yes,
        P = X - no
    ).