% Nub remove the repeated elements of a list
nub(X) -> nub(X, []).

nub([], XUnique) -> XUnique;
nub([X|Xs], XUnique) ->
    PositionWhereXFound = find(X, XUnique),
    if
        PositionWhereXFound > -1 ->
            nub(Xs, XUnique);
        true -> % 'else'
            nub(Xs, XUnique ++ [X])
    end.

% Find the item in a list
% Return the position where the first occurrence of Item is found
% Otherwise, return -1
find(_, []) -> -1;
find(Item, X) -> find(Item, X, 0).
find(Item, [Item|_Xs], Position) -> Position;
find(Item, [_X|Xs], Position) -> find(Item, Xs, Position + 1);
find(_, [], _) -> -1.