% Reference 9.6: string case and trim built-ins preserve non-letter characters.
%% goal: answer(X0, X1)

answer(lower_mixed, X) :- lowercase("Hello WORLD 123!", X).
answer(upper_mixed, X) :- uppercase("Hello world 123!", X).
answer(trim_spaces, X) :- trim("  padded  ", X).
answer(trim_tabs_newline, X) :- trim("\tvalue\n", X).
answer(trim_empty, X) :- trim("", X).