Goal:
  
  A : Type
  P : nat → A → A → Type
  i : nat
  hd : A
  hd' : A
  tl : list A
  p : P i hd hd'
  idx3 : nat
  idx4 : list A
  idx2 : list A
  ============================
   (∀ (b : OnOne2i P idx3 idx4 idx2) (H := CoreTactics.block) 
      (e : NoConfusion_OnOne2i A P
             {|
               pr1 :=
                 {|
                   pr1 := i; pr2 := {| pr1 := hd :: tl; pr2 := hd' :: tl |}
                 |};
               pr2 := OnOne2i_hd P i hd hd' tl p
             |}
             {|
               pr1 :=
                 {| pr1 := idx3; pr2 := {| pr1 := idx4; pr2 := idx2 |} |};
               pr2 := b
             |}),
      let H0 := CoreTactics.block in
      noConfusion_OnOne2i_obligation_2 A P
        {|
          pr1 :=
            {| pr1 := i; pr2 := {| pr1 := hd :: tl; pr2 := hd' :: tl |} |};
          pr2 := OnOne2i_hd P i hd hd' tl p
        |}
        {|
          pr1 := {| pr1 := idx3; pr2 := {| pr1 := idx4; pr2 := idx2 |} |};
          pr2 := b
        |}
        (noConfusion_OnOne2i_obligation_1 A P
           {|
             pr1 :=
               {| pr1 := i; pr2 := {| pr1 := hd :: tl; pr2 := hd' :: tl |} |};
             pr2 := OnOne2i_hd P i hd hd' tl p
           |}
           {|
             pr1 := {| pr1 := idx3; pr2 := {| pr1 := idx4; pr2 := idx2 |} |};
             pr2 := b
           |} e) = e)


DEBUG:Going to execute:
intros p