if_trace((case),(writeqln('case'=A))),
   ((eval_args(Eq,_UnkRetType,Depth,Self,A,AA),
         if_trace((case),writeqln('switch'=AA)),
    (select_case(Depth,Self,AA,KVs,Value)->true;(member(Void -Value,KVs),Void=='%void%')))
     *->true;(member(Void -Value,KVs),Void=='%void%')),
    eval_args(Eq,CaseRetType,Depth,Self,Value,Res).

  select_case(Depth,Self,AA,Cases,Value):-
     (best_key(AA,Cases,Value) -> true ;
      (maybe_special_keys(Depth,Self,Cases,CasES),
       (best_key(AA,CasES,Value) -> true ;
        (member(Void -Value,CasES),Void=='%void%')))).

  best_key(AA,Cases,Value):- member(Match-Value,Cases),AA = Match,!.
  best_key(AA,Cases,Value):-
     ((member(Match-Value,Cases),AA ==Match)->true;
      ((member(Match-Value,Cases),AA=@=Match)->true;
        (member(Match-Value,Cases),AA = Match))).

    into_case_list(CASES,CASES):- is_list(CASES),!.
        is_case(AA,[AA,Value],Value):-!.
        is_case(AA,[AA|Value],Value).

   maybe_special_keys(Depth,Self,[K-V|KVI],[AK-V|KVO]):-
     eval_args(Depth,Self,K,AK), K\=@=AK,!,
     maybe_special_keys(Depth,Self,KVI,KVO).
   maybe_special_keys(Depth,Self,[_|KVI],KVO):-
     maybe_special_keys(Depth,Self,KVI,KVO).
   maybe_special_keys(_Depth,_Self,[],[]).


% =================================================================
% =================================================================
% =================================================================
%  COLLAPSE/SUPERPOSE
% =================================================================
% =================================================================
% =================================================================

%;; collapse-bind because `collapse` doesnt guarentee shared bindings
eval_20(Eq,RetType,Depth,Self,['collapse-bind',List],Res):-!,
 maplist_ok_fails(eval_ne(Eq,RetType,Depth,Self),List,Res).

maplist_ok_fails(Pred2,[A|AA],BBB):- !,
 (call(Pred2,A,B) -> (BBB=[B|BB], maplist_ok_fails(Pred2,AA,BB))
   ; maplist_ok_fails(Pred2,AA,BBB)).
maplist_ok_fails(_Pred2,[],[]).

%;; superpose-bind because `superpose` doesnt guarentee shared bindings
% @TODO  need to keep bindings
eval_20(Eq,RetType,Depth,Self,['superpose-bind',List],Res):- !,
       re_member(Res,E,List),
       eval_ret(Eq,RetType,Depth,Self,E,Res).

re_member(Res,E,List):- term_variables(Res+E+List,TV),copy_term(TV,Copy),
    member(E,List),TV=Copy.

%[collapse,[1,2,3]]
eval_20(Eq,RetType,Depth,Self,['collapse',List],Res):-!,
 findall_eval(Eq,RetType,Depth,Self,List,Res).


eval_20(Eq,RetType,Depth,Self,['superpose',List],Res):- !,
       member(E,List),
       eval_ret(Eq,RetType,Depth,Self,E,Res).

%[superpose,[1,2,3]]
old_eval_20(_Eq,RetType,_Depth,_Self,['superpose',List],Res):- List==[], !,
  make_empty(RetType,[],Res).
old_eval_20(Eq,RetType,Depth,Self,['superpose',List],Res):- !,
  (((
   is_user_defined_head(Eq,Self,List) ,eval_args(Eq,RetType,Depth,Self,List,UList),