∀ {G : Type u_1} {X : Type u_2} [inst : MeasurableSpace X] {μ : MeasureTheory.Measure X} [inst_1 : Group G]
  [inst_2 : MulAction G X] {ι : Type u_3} {u : Ultrafilter ι} {F : ι → Set X},
  IsFoelner G μ (↑u) F → IsFoelner.mean μ u F Set.univ = 1