∀ {α : Type u_1} {γ : Type u_3} [inst : MeasurableSpace α] {μ : MeasureTheory.Measure α} [inst_1 : TopologicalSpace γ]
  [inst_2 : LinearOrder γ] [inst_3 : OrderClosedTopology γ] [inst_4 : Zero γ] (f : α →ₘ[μ] γ),
  ↑f.posPart =ᵐ[μ] fun a => max (↑f a) 0