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
  ============================
   ((∀ 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:
intro_block_id H || intro_block H
Level 0: Backtrace:

No quantified hypothesis named H in current goal even after head-reduction.
Level 0: Backtrace:

No quantified hypothesis named H in current goal even after head-reduction.