∀ {M : Type u_1} {P : Type u_3} [inst : AddZeroClass M] [inst_1 : AddZeroClass P] (f : M →+ P)
  (hf : Function.Surjective ⇑f),
  AddCon.quotientKerEquivOfSurjective f hf = AddCon.quotientKerEquivOfRightInverse f (Exists.choose ⋯) ⋯