Goal:
    A : Type  B : Type  C : Type  R : A → B → C → Type  H : True
  ============================
   (All3_nil = All3_nil)


DEBUG:Going to execute:
intro_block_id H || intro_block H
Level 4: Backtrace:

No quantified hypothesis named H in current goal even after head-reduction.
Level 4: Backtrace:

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