Goal:
  
  A : Type
  P : nat → A → A → Type
  i : nat
  hd : A
  hd' : A
  tl : list A
  p : P i hd hd'
  i0 : nat
  hd0 : A
  tl0 : list A
  tl' : list A
  b : OnOne2i P (S i0) tl0 tl'
  H : False
  ============================
   ({|
      pr1 := {| pr1 := i; pr2 := {| pr1 := hd :: tl; pr2 := hd' :: tl |} |};
      pr2 := OnOne2i_hd P i hd hd' tl p
    |} =
    {|
      pr1 :=
        {| pr1 := i0; pr2 := {| pr1 := hd0 :: tl0; pr2 := hd0 :: tl' |} |};
      pr2 := OnOne2i_tl P i0 hd0 tl0 tl' b
    |})


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