Goal:
  
  A : Type
  p : nat → A → bool
  q : nat → A → bool
  l : list A
  l' : list A
  n : nat
  ============================
   (alli p n l = alli (λ i : nat, p (n + i)) 0 l)


DEBUG:Going to execute:
induction l in n, p |- *; simpl