∀ {C : Type u_2} [inst : CategoryTheory.Bicategory C] (X : C) {X_1 Y : X ⟶ X} (f : X_1 ⟶ Y),
  CategoryTheory.CategoryStruct.comp (CategoryTheory.Bicategory.whiskerLeft (CategoryTheory.CategoryStruct.id X) f)
      (CategoryTheory.Bicategory.leftUnitor Y).hom =
    CategoryTheory.CategoryStruct.comp (CategoryTheory.Bicategory.leftUnitor X_1).hom f