fact: Definition pullback_to_binprod : some_pullback C Z → some_binprod (C / Z).
imports: UniMath.MoreFoundations.Tactics UniMath.Foundations.Sets UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.slicecat UniMath.CategoryTheory.Equivalences.Core UniMath.CategoryTheory.Limits.BinProducts UniMath.CategoryTheory.Limits.Pullbacks