Goal:
    A : Type  P : A → Prop  p : A → bool  q : A → bool
  ============================
   ((∀ x : A, P x → p x = q x) → true = true)


DEBUG:Going to execute:
match goal with
           | |- ?X1 → ?X2 => intro
           | |- ¬ _ => unfold not at 1; intro
           end