∀ {α : Type u_1} {β : Type u_2} {γ : Type u_3} [inst : TopologicalSpace α] [inst_1 : TopologicalSpace β]
  [inst_2 : TopologicalSpace γ] [inst_3 : Add γ] [inst_4 : ContinuousAdd γ] (f₁ f₂ : C(β, γ)) (g : C(α, β)),
  (f₁ + f₂).comp g = f₁.comp g + f₂.comp g