exp(F):-not(sub_string(F,_,_,_,"?")),write("Diagnose: "),write(F),nl.
exp(F):-write(F),write(" "),read(A),clause(dat(F,A,Fn),true),exp(Fn).
exp(F):-write("Antwort wiederholen oder #: "),read(A),write("Neue Frage: "),
         read(Fn),asserta(dat(F,A,Fn)),exp(Fn).
anf:-exp("krank?").