∀ {X : Type u} {Y : Type v} {Z : Type u_2} [inst : TopologicalSpace X] [inst_1 : TopologicalSpace Y]
  [inst_2 : TopologicalSpace Z] (a : X × Z ⊕ Y × Z),
  Homeomorph.sumProdDistrib.symm a = (Equiv.sumProdDistrib X Y Z).symm a