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<div class="nb-cell program" data-background="true" name="p1">
p( 301, 1, 2 ).
p( 201, 5, 2 ).
p( 501, 1, 5 ).
p( 401, 1, 4 ).

patients(L) :-
    findall(p(A,B,C), p(A,B,C), L).
</div>

<div class="nb-cell program" name="p2">
group_by_arg3(Terms, Grouped) :-
    map_list_to_pairs(arg(3), Terms, Keyed),
    keysort(Keyed, Sorted),
    group_pairs_by_key(Sorted, KeyGrouped),
    pairs_values(KeyGrouped, Grouped).
</div>

<div class="nb-cell query" name="q1">
projection([G]),
patients(L), group_by_arg3(L, G).
</div>

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