fact: Definition continuous2d {U V W : TopologicalSpace} (f : U → V → W) := ∏ (x : U) (y : V), continuous2d_at f x y.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Topology.Filters UniMath.Algebra.Groups UniMath.Algebra.DivisionRig UniMath.Algebra.ConstructiveStructures