fact: Definition FiniteSetSum {I : FiniteSet} (X : I -> FiniteSet) : FiniteSet.
imports: UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.DecidablePropositions UniMath.MoreFoundations.NegativePropositions UniMath.Combinatorics.StandardFiniteSets UniMath.MoreFoundations.Subtypes