fact: Definition Cocomma {A : Category} {B : Category} {C : Category} {S : A ⟶ C} {T : B ⟶ C} := @Comma (B^op) (A^op) (C^op) (T^op) (S^op).
imports: Category.Lib Category.Theory.Category Category.Theory.Isomorphism Category.Theory.Functor Category.Theory.Natural.Transformation Category.Construction.Product Category.Construction.Opposite Category.Functor.Opposite