Goal:
  
  A : Type
  B : Type
  C : Type
  Q : C → Type
  P : C → A → Prop
  fn : ∀ x : A, (∀ y : C, Q y → P y x) → B
  Hl : ∀ y : C, Q y → ∥ All (P y) [] ∥
  ============================
   (let H := CoreTactics.block in #|map_All fn [] Hl| = #|[]|)


DEBUG:Going to execute:
DepElim.simplify_one_dep_elim