Ltac prove_it_now :=
 first [ splittable; fail 1
        | computable
        | apply Coq.Init.Logic.I
        | reflexivity
        | rewrite ?intsigned_intrepr_bytesigned; rep_omega (* Omega0 *)
        | prove_signed_range
        | repeat match goal with H: ?A |- _ => has_evar A; clear H end;
          auto with prove_it_now field_compatible;
          autorewrite with norm entailer_rewrite; normalize;
          first [eapply field_compatible_nullval; eassumption
                 | eapply field_compatible_nullval1; eassumption
                 | eapply field_compatible_nullval2; eassumption
                 ]
         ].Ltac try_prove_it_now :=
 first [match goal with H := _ |- _ => instantiate (1:=True) in H; prove_it_now end
       | eassumption].

Lemma try_conjuncts_start: forall A B: Prop, (A -> B) -> (A -> B).