Goal:
    A : Type  P : list A → list A → A → A → Type  H : True
  ============================
   ({| pr1 := {| pr1 := []; pr2 := [] |}; pr2 := All2_fold_nil P |} =
    {| pr1 := {| pr1 := []; pr2 := [] |}; pr2 := All2_fold_nil P |})


DEBUG:Going to execute:
hnf in id
Level 5: evaluation returns
hnf in id; CoreTactics.destruct_tele_eq id || destruct id
where
id := H
of type
constr
b := b
of type
constr
a := a
of type
constr
R := eq
of type
constr of type tacvalue