∀ {B : Type u} [inst : CategoryTheory.Bicategory B] {x y z t : B} (e₁ : x = y) (e₂ : y = z) (e₃ : z = t),
  (CategoryTheory.Bicategory.associator (CategoryTheory.eqToHom e₁) (CategoryTheory.eqToHom e₂)
        (CategoryTheory.eqToHom e₃)).hom =
    CategoryTheory.CategoryStruct.comp
      (CategoryTheory.Bicategory.whiskerRight (CategoryTheory.Bicategory.eqToHomTransIso e₁ e₂).inv
        (CategoryTheory.eqToHom e₃))
      (CategoryTheory.CategoryStruct.comp (CategoryTheory.Bicategory.eqToHomTransIso ⋯ e₃).inv
        (CategoryTheory.CategoryStruct.comp (CategoryTheory.Bicategory.eqToHomTransIso e₁ ⋯).hom
          (CategoryTheory.Bicategory.whiskerLeft (CategoryTheory.eqToHom e₁)
            (CategoryTheory.Bicategory.eqToHomTransIso e₂ e₃).hom)))