filter_test(Filtered):-
    words(Words),
    filter_list(Words, 97, []).

filter(Words, Char, Filtered):-
    filter(Words, Char, [], Filtered).

filter([], Char, RecurFiltered, Filtered):-
    Filtered = RecurFiltered.

filter([H|T], Char, RecurFiltered, Filtered):-
    atom_codes(H, Word),
    Word = [FirstChar|Rest],
    (FirstChar \= H ->
        filter(T, Char, RecurFiltered, Filtered)
    ;
        filter(T, Char, [Rest|RecurFiltered], Filtered)
    ).