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'
  ============================
   ((let eq_opt_elt :=
       fun x y : option elt =>
       match x with
       | Some x0 =>
           match y with
           | Some y0 => eq_elt x0 y0
           | None => False
           end
       | None => match y with
                 | Some _ => False
                 | None => True
                 end
       end in
     (forall k : key, In k m -> eq_opt_elt (find k m) (find k m')) /\
     (forall k : key, In k m' -> eq_opt_elt (find k m) (find k m'))) <->
    (forall k : key,
     (exists e : elt, find k m = Some e) <->
     (exists e : elt, find k m' = Some e)) /\
    (forall (k : key) (e e' : elt),
     find k m = Some e -> find k m' = Some e' -> eq_elt e e'))


DEBUG:Going to execute:
cbv[In]