delete(A, [A|B], B).
delete(B, [A|C], [A|D]) :-
delete(B, C, D).
add(A, B, [A|B]).
make_node(Name,List) :-
add(element(Name, [], []), [], List),
X=..List,
assert(X),
write(List).
make_node(Name, Attr, Cont, List) :-
add(element(Name, Attr, Cont), [], List),
X=..List,
assert(X),
write(List).
add_child(Parent,Child,Nlist):-
element(Parent,A,C),
retract(element(Parent,A,C)),
add(element(Child,[],[]),C,L),
make_node(Parent,A,L,Nlist).
add_child(Parent,Child,Ch_att,Ch_cont,Nlist):-
element(Parent,A,C),
retract(element(Parent,A,C)),
add(element(Child,Ch_att,Ch_cont),C,L),
make_node(Parent,A,L,Nlist).
make_list(List) :-
bagof(A,element(A,B,C),A),
L=..A,
add(element(L,B,C),[],List),
write(List).
save :-
tell('wiedza.pl'),
listing(element),
told.
prolog2xml(List,File):-
tell(File),
open(File,write,S),
xml_write(S,List,[]),
told,
close(S).
----------------------------------
add_child(Parent,Child,Nlist):-
element(Parent,A,C),
element(Child,Chatt,Chcont),
retract(element(Parent,A,C)),
retract(element(Child,Chatt,Chcont)),
add(element(Child,Chatt,Chcont),C,L),
make_node(Parent,A,L,Nlist).
add_child(Parent,A,Child,Chatt,Nlist):-
element(Parent,A,C),
element(Child,Chatt,Chcont),
retract(element(Parent,A,C)),
retract(element(Child,Chatt,Chcont)),
add(element(Child,Chatt,Chcont),C,L),
make_node(Parent,A,L,Nlist).