Definition setTfor (phT : phant T) := [set x : T | true].

Lemma eq_in_imset2 (f g : aT -> aT2 -> rT) (D : pred aT) (D2 : pred aT2) :
{in D & D2, f =2 g} -> f @2: (D, D2) = g @2: (D, D2).