∀ {𝕜 : Type u_1} {E : Type u_2} {M : Type u_3} {H : Type u_4} [inst : NontriviallyNormedField 𝕜]
  [inst_1 : NormedAddCommGroup E] [inst_2 : NormedSpace 𝕜 E] [inst_3 : TopologicalSpace H] [inst_4 : TopologicalSpace M]
  {I : ModelWithCorners 𝕜 E H} {e e' : OpenPartialHomeomorph M H} {x : M},
  x ∈ e.source →
    x ∈ e'.source → (ModelWithCorners.extendCoordChange e e').source ∈ nhdsWithin (↑(e.extend I) x) (Set.range ↑I)