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'
  k : key
  x : elt
  x0 : elt
  H3 : eq_elt x0 x
  H1 : find k m' = Some x
  x1 : elt
  H4 : find k m' = Some x1
  H5 : find k m = Some x0
  H2 : forall k : key, find k m' = find k m'
  H6 : forall k : key, find k m = find k 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


DEBUG:Going to execute:
PTRDEBUGTACidtac
Level 3: evaluation returns
idtac;
 match goal with
 | H:_
   |- _ =>
       guard_tac H;
        guarded_specialize_gen_hyp_under_binders_by all_ways
         ltac:(guard_nondep) H tac
 end
where
tac := exact H
       where
       H := H1
       of type
       constr
of type
tacvalue
guard_tac := fun _ => idtac
             where
             tac := exact H
                    where
                    H := H1
                    of type
                    constr
             of type
             tacvalue
             all_ways := false
             of type
             constr
of type
tacvalue
all_ways := false
of type
constr of type tacvalue

Level 2: evaluation returns
idtac;
 match goal with
 | H:_
   |- _ =>
       guard_tac H;
        guarded_specialize_gen_hyp_under_binders_by all_ways
         ltac:(guard_nondep) H tac
 end
where
tac := exact H
       where
       H := H1
       of type
       constr
of type
tacvalue
guard_tac := fun _ => idtac
             where
             tac := exact H
                    where
                    H := H1
                    of type
                    constr
             of type
             tacvalue
             all_ways := false
             of type
             constr
of type
tacvalue
all_ways := false
of type
constr of type tacvalue