/* Le zig-zag */
zig(a) :- write('un '), write('deux '), write('trois'), nl.
zig(b) :- write('quatre '), write('cinq '), write('six'), nl.
zig(c) :- write('sept'), nl, write(fini_pour_zig), nl.

zigzag(X, Y) :- 
        zig(X), write('X = '), write(X), nl,
        zig(Y), write('Y = '), write(Y), nl.
