Goal:
    A : Type  P : list A → list A → A → A → Type
  ============================
   (let H := CoreTactics.block in
    let H0 := CoreTactics.block in
    All_fold (λ (Γ : list A) (d : A), P Γ Γ d d) [])


DEBUG:Going to execute:
match goal with
           | hyp:context [ CoreTactics.block ]
             |- _ =>
                 cbn beta in hyp; eqns_specialize_eqs_block hyp;
                  cbn[eq_rect_r eq_rect] in hyp
           end