fact: Definition pair_equivalence_of_cats_unit : functor_identity (category_binproduct C₁ C₂) ⟹ L ∙ R.
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.MoreFoundations.PartA UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Adjunctions.Core UniMath.CategoryTheory.Equivalences.Core UniMath.CategoryTheory.whiskering UniMath.CategoryTheory.PrecategoryBinProduct