id_memberchk_kv( [K-V|_T], M-V1 ) :-
	K == M,
	!,
	V1 = V.
id_memberchk_kv( [_H|T], M ) :-
	id_memberchk_kv( T, M ).

id_memberchk( [H|_T], El ) :-
	H == El,
	!.
id_memberchk( [_H|T], El ) :-
	id_memberchk( T, El ).

id_select(ElK-ElV, [K-V|Tail], Tail) :-
	ElK == K,
	!, 
	ElV = V.
id_select(Element, [Head|Tail1], [Head|Tail2]) :- 
	id_select(Element, Tail1, Tail2).