proposition: Lemma near_ball (y : M) (eps : R) : 0 < eps -> \forall y' \near y, ball y eps y'.
proof: Proof. exact: nbhsx_ballx. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed