theorem MeasureTheory.measure_eq_univ_of_forall_singleton {Ω : Type u_1} [Countable Ω] [MeasurableSpace Ω] {μ : Measure Ω} {s : Set Ω} (hμ : ∀ x ∈ sᶜ, μ {x} = 0) : μ s = μ Set.univ