Goal:
  
  A : Type
  B : Type
  C : Type
  P : A → B → C → Prop
  p : A → B → C → bool
  Hp : ∀ (x : A) (y : B) (z : C), reflect (P x y z) (p x y z)
  ============================
   (true → Forall3 P [] [] [])


DEBUG:Going to execute:
done
DEBUG LTAC Evaluated term: Prop
DEBUG LTAC Evaluated term: Prop
DEBUG LTAC Evaluated term: Prop
DEBUG LTAC Evaluated term: Prop