fact: Definition Union_Encode {m} (encoders : Vector.t (EncodeM S T) m) (idx : S -> Fin.t m) : EncodeM S T := fun s => Vector.nth encoders (idx s) s.
imports: Fiat.Common.ilist Fiat.Common.IterateBoundedIndex Fiat.Narcissus.Common.Specs Coq.Sets.Ensembles