Instance forAllMonotonic {A C} {_ : Checkable C} `{Show A} (g : G A) (f : A -> C)
        `{SizeMonotonic _ g} `{forall x, SizeMonotonicChecker (checker (f x))} :
  SizeMonotonicChecker (forAll g f).

Lemma eq_to_impl : forall (a b : Prop), a = b -> a -> b.