Goal:
    A : Type  p : A → bool  l : list A
  ============================
   (Forall (λ x : A, p x) l → forallb p l)


DEBUG:Going to execute:
induction 1

Goals:
    A : Type  p : A → bool
  ============================
   (is_true (forallb p []))

  
  A : Type
  p : A → bool
  x : A
  l : list A
  H : is_true (p x)
  H0 : Forall (λ x : A, p x) l
  IHForall : is_true (forallb p l)
  ============================
   (is_true (forallb p (x :: l)))


DEBUG:Going to execute:
rewrite /= // H IHForall //