fact: Variable FiniteSetImpl : FullySharpened FiniteSetSpec.
imports: Coq.Strings.String Coq.Sets.Ensembles Coq.Sets.Finite_sets Coq.Lists.List Coq.Sorting.Permutation Fiat.ADT Fiat.ADT.ComputationalADT Fiat.ADTRefinement.Core Fiat.ADTNotation Fiat.ADTRefinement.GeneralRefinements Fiat.Common.Ensembles Fiat.FiniteSetADTs.FiniteSetADT Fiat.Common.Ensembles.Notations Fiat.Common.Ensembles.Equivalence