fact: Definition nelstruct (n : nat) (X : UU) : UU := ⟦ n ⟧ ≃ X.
imports: UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.DecidablePropositions UniMath.MoreFoundations.NegativePropositions UniMath.Combinatorics.StandardFiniteSets UniMath.MoreFoundations.Subtypes