Goal:
  
  A : Type
  f : nat → A → bool
  g : nat → A → bool
  fg : f =2 g
  y : nat
  y0 : list A
  ============================
   (∀ i : nat, f i =1 g i)


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"