append([Temp1 | Temp2] , Temp3, L)

chopTree(leaf(_), []).
chopTree(node1(Leaf, Node), L) :-
    chopTree(Node, Temp),
    append([], [Leaf | Temp], L).
chopTree(node2(Leaf, Node1, Node2), L) :-
    chopTree(Node1, Temp1),
    chopTree(Node2, Temp2),
    append(Temp1, [Leaf | Temp2], L).
chopTree(node3(_, Node1, Node2, Node3), L) :-
    chopTree(Node1, Temp1),
    chopTree(Node2, Temp2),
    chopTree(Node3, Temp3),
    append([Temp1 | Temp2] , Temp3, L).

query :-
    chopTree(node3(1,
                   node1(2, leaf(1)),
                   node2(3, leaf(1), leaf(1)),
                   node1(4, leaf(1))),
             E).