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:- module lpe_example.
:- interface.
:- import_module io.

:- pred main(io__state::di, io__state::uo) is det.

:- implementation.

:- import_module solutions.
:- import_module int.

main -->
    { solutions(p(1), Ss) },
    io__write(Ss),
    io__nl.

:- pred p(int, int).
:- mode p(in, out) is nondet.

p(0, 0).
p(1, X) :-
    q(A),
    (
        r(A, X)
    ;
        X = A
    ).

:- pred q(int).
:- mode q(out) is det.

q(3).

:- pred r(int, int).
:- mode r(in, out) is multi.

r(X, X + 10).
r(X, X + 20).