fact: Definition opt_to_list n := match nat_enum n with Some x => [x] | None => [] end.
imports: Undecidability.L(Computability.MuRec) Undecidability.L.Datatypes(LNat LOptions LProd) Undecidability.Synthetic(DecidabilityFacts EnumerabilityFacts ListEnumerabilityFacts ReducibilityFacts) Undecidability.L.Datatypes.List(List_basics List_nat) Datatypes