fact: Definition weqfrom2cellalttoidalgmap {XX YY : algebra_ob P} (ff gg : algebra_mor P XX YY) : algebra_2cellalt ff gg ≃ ff = gg.
imports: UniMath.Foundations.All UniMath.Induction.PolynomialFunctors UniMath.CategoryTheory.Core.Functors UniMath.Induction.FunctorAlgebras_legacy