Goal:
  
  A : Type
  l3 : list A
  R1 : A → A → Type
  R2 : A → A → Type
  R3 : A → A → Type
  hd : A
  tl : list A
  tl' : list A
  o : OnOne2 R1 tl tl'
  IHo : ∀ l3 : list A,
          All2 R2 tl l3
          → (∀ x y : A, R2 x y → R3 x y)
            → (∀ x y z : A, R1 x y → R2 x z → R3 y z) → All2 R3 tl' l3
  H : All2 R2 (hd :: tl) l3
  ============================
   (let H := CoreTactics.block in
    let H0 := CoreTactics.block in
    (∀ x y : A, R2 x y → R3 x y)
    → (∀ x y z : A, R1 x y → R2 x z → R3 y z) → All2 R3 (hd :: tl') l3)


DEBUG:Going to execute:
get_signature_pack id id'; hnf in (value of id');
            hnf in (type of id')
Level 3: evaluation returns
get_signature_pack id id'; hnf in (value of id'); hnf in (type of id');
 lazymatch goal with
 | id':=?v:_
   |- context [ id ] =>
       generalize (eq_refl : v = id'); clearbody id'; simpl in id';
        cont id id' id v
 | id':=?v:_
   |- _ =>
       let id'1 := fresh id' in
       let id'2 := fresh id' in
       set (id'2 := pr2 id'); set (id'1 := pr1 id') in id'2;
        hnf in (value of id'1), (value of id'2); try red in (type of id'2);
        match goal with
        | id'1:=?t:_
          |- _ =>
              generalize (eq_refl : t = id'1); clearbody id'2 id'1; clear id'
               id; try unfold signature in id'2; hnf in id'2; 
               simpl in id'2; rename id'2 into id; 
               cont id id id'1 t
        end
 end
where
id' := H0
of type
intropattern
id := H
of type
ident
cont := fun id id' id'1 t => try rename id into id',id' into id; cont id'1 id
        where
        id := H
        of type
        ident
        cont := fun id id' => DepElim.decompose_exists id id'
                where
                id := H
                of type
                ident
        of type
        tacvalue
of type
tacvalue of type tacvalue

Level 2: evaluation returns
get_signature_pack id id'; hnf in (value of id'); hnf in (type of id');
 lazymatch goal with
 | id':=?v:_
   |- context [ id ] =>
       generalize (eq_refl : v = id'); clearbody id'; simpl in id';
        cont id id' id v
 | id':=?v:_
   |- _ =>
       let id'1 := fresh id' in
       let id'2 := fresh id' in
       set (id'2 := pr2 id'); set (id'1 := pr1 id') in id'2;
        hnf in (value of id'1), (value of id'2); try red in (type of id'2);
        match goal with
        | id'1:=?t:_
          |- _ =>
              generalize (eq_refl : t = id'1); clearbody id'2 id'1; clear id'
               id; try unfold signature in id'2; hnf in id'2; 
               simpl in id'2; rename id'2 into id; 
               cont id id id'1 t
        end
 end
where
id' := H0
of type
intropattern
id := H
of type
ident
cont := fun id id' id'1 t => try rename id into id',id' into id; cont id'1 id
        where
        id := H
        of type
        ident
        cont := fun id id' => DepElim.decompose_exists id id'
                where
                id := H
                of type
                ident
        of type
        tacvalue
of type
tacvalue of type tacvalue

Level 1: evaluation returns
get_signature_pack id id'; hnf in (value of id'); hnf in (type of id');
 lazymatch goal with
 | id':=?v:_
   |- context [ id ] =>
       generalize (eq_refl : v = id'); clearbody id'; simpl in id';
        cont id id' id v
 | id':=?v:_
   |- _ =>
       let id'1 := fresh id' in
       let id'2 := fresh id' in
       set (id'2 := pr2 id'); set (id'1 := pr1 id') in id'2;
        hnf in (value of id'1), (value of id'2); try red in (type of id'2);
        match goal with
        | id'1:=?t:_
          |- _ =>
              generalize (eq_refl : t = id'1); clearbody id'2 id'1; clear id'
               id; try unfold signature in id'2; hnf in id'2; 
               simpl in id'2; rename id'2 into id; 
               cont id id id'1 t
        end
 end
where
id' := H0
of type
intropattern
id := H
of type
ident
cont := fun id id' id'1 t => try rename id into id',id' into id; cont id'1 id
        where
        id := H
        of type
        ident
        cont := fun id id' => DepElim.decompose_exists id id'
                where
                id := H
                of type
                ident
        of type
        tacvalue
of type
tacvalue of type tacvalue