fact: Definition folds_iso (a b : C) := ∑ i : folds_iso_data a b, folds_iso_prop i.
imports: UniMath.Folds.UnicodeNotations UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.Foundations.Sets UniMath.Foundations.UnivalenceAxiom UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.Folds.folds_precat UniMath.Folds.from_precats_to_folds_and_back