proposition: Lemma near_withinT F D : Filter F -> \forall x \near within D F, D x.
proof: Proof. exact: withinT. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed