∀ {X : Type u_1} (self : DiffeologicalSpace.CorePlotsOn X) {n : ℕ} {u : Set (EuclideanSpace ℝ (Fin n))} (hu : IsOpen u)
  {p q : EuclideanSpace ℝ (Fin n) → X}, Set.EqOn p q u → (self.isPlotOn hu p ↔ self.isPlotOn hu q)