Goal:
  
  A : Type
  P : nat → A → Type
  k : nat
  l : list A
  alli : Alli (λ k' : nat, P (Nat.pred #|l| - k' + k)) 0 l
  ============================
   (Alli (λ k' : nat, P (Nat.pred #|l| - k' + k)) 0 l)


DEBUG:Going to execute:
let rec do_ccl :=
            try do_atom; repeat (do_intro; try do_atom); try arith_congr;
             (solve [ split; do_ccl ])
           in
           (solve [ do_atom | use_hyps; do_ccl ]) ||
             fail "Cannot solve this goal"