Goal:
    A : Type  P : list A → list A → A → A → Type
  ============================
   (∀ (H := CoreTactics.block) (e : NoConfusion_All2_fold A P
                                      {|
                                        pr1 := {| pr1 := []; pr2 := [] |};
                                        pr2 := All2_fold_nil P
                                      |}
                                      {|
                                        pr1 := {| pr1 := []; pr2 := [] |};
                                        pr2 := All2_fold_nil P
                                      |}),
      let H0 := CoreTactics.block in
      noConfusion_All2_fold_obligation_2 A P
        {| pr1 := {| pr1 := []; pr2 := [] |}; pr2 := All2_fold_nil P |}
        {| pr1 := {| pr1 := []; pr2 := [] |}; pr2 := All2_fold_nil P |}
        (noConfusion_All2_fold_obligation_1 A P
           {| pr1 := {| pr1 := []; pr2 := [] |}; pr2 := All2_fold_nil P |}
           {| pr1 := {| pr1 := []; pr2 := [] |}; pr2 := All2_fold_nil P |} e) =
      e)


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