fact: Definition locally2d {T S : TopologicalSpace} (x : T) (y : S) : Filter (T × S) := FilterDirprod (locally x) (locally y).
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Topology.Filters UniMath.Algebra.Groups UniMath.Algebra.DivisionRig UniMath.Algebra.ConstructiveStructures