∀ {C₁ : Type u₁} {C₂ : Type u₂} [inst : CategoryTheory.Category.{v₁, u₁} C₁]
  [inst_1 : CategoryTheory.Category.{v₂, u₂} C₂] (F : CategoryTheory.Functor C₁ C₂),
  (CategoryTheory.TwoSquare.mk F (CategoryTheory.Functor.id C₁) (CategoryTheory.Functor.id C₂) F
      (CategoryTheory.CategoryStruct.id F)).GuitartExact