∀ {B : Type u_2} [inst : CategoryTheory.Bicategory B] {F : CategoryTheory.Pseudofunctor B CategoryTheory.Cat}
  (P : F.ObjectProperty) [inst_1 : P.IsClosedUnderMapObj] {a b : B} (f : a ⟶ b),
  { toNatTrans := P.map₂ (CategoryTheory.Bicategory.leftUnitor f).hom } =
    CategoryTheory.CategoryStruct.comp
      (CategoryTheory.Cat.Hom.isoMk (P.mapComp (CategoryTheory.CategoryStruct.id a) f)).hom
      (CategoryTheory.CategoryStruct.comp
        (CategoryTheory.Bicategory.whiskerRight (CategoryTheory.Cat.Hom.isoMk (P.mapId a)).hom { toFunctor := P.map f })
        (CategoryTheory.Bicategory.leftUnitor { toFunctor := P.map f }).hom)