Goal:
  
  A : Type
  P : list A → list A → A → A → Type
  d : A
  d' : A
  Γ : list A
  Γ' : list A
  b : All2_fold P Γ Γ'
  p : P Γ Γ' d d'
  H : False
  ============================
   ({| pr1 := {| pr1 := []; pr2 := [] |}; pr2 := All2_fold_nil P |} =
    {|
      pr1 := {| pr1 := d :: Γ; pr2 := d' :: Γ' |};
      pr2 := All2_fold_cons P b p
    |})


DEBUG:Going to execute:
match type of H with
           | ?R ?x ?y =>
               let rhs := fresh in
               set (rhs := y) in *; pattern sigma rhs; clearbody rhs;
                destruct H; simpl
           end