Goal:
  
  elt : Type
  eq_elt : elt -> elt -> Prop
  m : t elt
  m' : t elt
  H : forall x y : key, E.eq x y -> find x m = find y m
  H0 : forall x y : key, E.eq x y -> find x m' = find y m'
  H1 : forall k : key,
       (exists (e : elt) (y : key × elt),
          (E.eq k y.1 /\ e = y.2) /\ List.In y (elements m)) ->
       match find k m with
       | Some x =>
           match find k m' with
           | Some y => eq_elt x y
           | None => False
           end
       | None => match find k m' with
                 | Some _ => False
                 | None => True
                 end
       end
  H3 : forall k : key,
       (exists (e : elt) (y : key × elt),
          (E.eq k y.1 /\ e = y.2) /\ List.In y (elements m')) ->
       match find k m with
       | Some x =>
           match find k m' with
           | Some y => eq_elt x y
           | None => False
           end
       | None => match find k m' with
                 | Some _ => False
                 | None => True
                 end
       end
  k : key
  e : elt
  H2 : List.In (k, e) (elements m')
  ============================
   ?T0


DEBUG:Going to execute:
match goal with
           | _ =>
               let __ := lazymatch goal with
                         | _ => guard_tac H
                         end in
               open_constr:((H ltac:((progress tac))))
           | _ =>
               let H := open_constr:((H _)) in
               guarded_specialize_term_under_binders_by' guard_tac H tac
           end
DEBUG LTAC Evaluated term: H3
DEBUG LTAC Evaluated term: (forall k : key,
                            (exists (e : elt) (y : key × elt),
                               (E.eq k y.1 /\ e = y.2) /\
                               List.In y (elements m')) ->
                            match find k m with
                            | Some x =>
                                match find k m' with
                                | Some y => eq_elt x y
                                | None => False
                                end
                            | None =>
                                match find k m' with
                                | Some _ => False
                                | None => True
                                end
                            end)
Level 3: type of H
 has value 
(forall k : key,
 (exists (e : elt) (y : key × elt),
    (E.eq k y.1 /\ e = y.2) /\ List.In y (elements m')) ->
 match find k m with
 | Some x => match find k m' with
             | Some y => eq_elt x y
             | None => False
             end
 | None => match find k m' with
           | Some _ => False
           | None => True
           end
 end)