Goal:
    A : Type  P : A → Prop  l : list A  H : Forall P l
  ============================
   (∀ n : nat, Forall P (firstn n l))


DEBUG:Going to execute:
induction H

Goals:
    A : Type  P : A → Prop
  ============================
   (∀ n : nat, Forall P (firstn n []))

  
  A : Type
  P : A → Prop
  x : A
  l : list A
  H : P x
  H0 : Forall P l
  IHForall : ∀ n : nat, Forall P (firstn n l)
  ============================
   (∀ n : nat, Forall P (firstn n (x :: l)))


DEBUG:Going to execute:
intros n
DEBUG LTAC Evaluated term: H