Goal:
  
  A : Type
  B : Type
  R : A → B → Type
  R' : ∀ (a : A) (b : B), R a b → Type
  ============================
   (eq_refl = eq_refl)


DEBUG:Going to execute:
repeat
            progress
             autorewrite with refl_id || (try DepElim.rewrite_sigma2_refl)