blurt(X) :- print(X),nl. %flush_output.

error(X) :- warning(X),fail.
warning(X) :-
	source_location(File, Line)
    -> file_base_name(File,Base),
	   format('% ?? ~w, line ~w: ~w\n',[Base,Line,X])
    ;  format('% ??  ~w\n',[X]).