fact: Definition preserves_left_Kan `(L : E ⟶ F) := ∀ C D (G : C ⟶ E) (K : C ⟶ D) `(!LeftKan K E) `(!LeftKan K F), L ◯ Lan K G ≈ Lan K (L ◯ G).
imports: Category.Lib Category.Theory.Category Category.Theory.Isomorphism Category.Theory.Functor Category.Theory.Natural.Transformation Category.Theory.Adjunction Category.Instance.Fun Category.Instance.Sets