?- dynamic(puffer/1).

alle_re(_, _, _)         :- asserta(puffer(mark)),
                            fail.
alle_re(X, Anfrage_X, _) :- Anfrage_X,
                            asserta( puffer(X) ),
                            fail.
alle_re(_, _, L)         :- sammeln_re([], L).

sammeln_re(L1, L2) :- retract( puffer(X) ),
                      (X \= mark, !, sammeln_re([X|L1], L2);
                       !, L1 = L2).