-- Lean 4 proof step from Mathlib.Algebra.Homology.BifunctorShift (goal)
Goal:
C₁ : Type u_1
C₂ : Type u_2
D : Type u_3
inst : Category.{v_1, u_1} C₁
inst_1 : Category.{v_2, u_2} C₂
inst_2 : Category.{v_3, u_3} D
inst_3 : Preadditive.{v_1, u_1} C₁
inst_4 : Preadditive.{v_2, u_2} C₂
inst_5 : Preadditive.{v_3, u_3} D
K₁ : CochainComplex.{v_1, u_1, 0} C₁ ℤ
K₂ : CochainComplex.{v_2, u_2, 0} C₂ ℤ
F : C₁ ⥤ CategoryTheory.Functor.{v_2, v_3, u_2, u_3} C₂ D
inst_6 : F.Additive
inst_7 : ∀ (X₁ : C₁), (F.obj X₁).Additive
x y : ℤ
inst_8 : K₁.HasMapBifunctor K₂ F
⊢ Iso.hom
      (Iso.trans (Y :=
        Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
          (K₁.mapBifunctor (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F))
        (K₁.mapBifunctorShift₁Iso (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F
            x :
          Iso (C := CochainComplex.{v_3, u_3, 0} D ℤ)
            ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor
              (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F)
            (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
              (K₁.mapBifunctor (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F)))
        (Functor.mapIso (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
            (K₁.mapBifunctorShift₂Iso K₂ F y) :
          Iso (C := CochainComplex.{v_3, u_3, 0} D ℤ)
            (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
              (K₁.mapBifunctor (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F))
            (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
              (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                (K₁.mapBifunctor K₂ F))))) =
    (HSMul.hSMul (β :=
        Iso (C := CochainComplex.{v_3, u_3, 0} D ℤ)
          ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor
            (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F)
          (Functor.obj
            (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y ⋙
              CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
            (K₁.mapBifunctor K₂ F)))
        (x * y).negOnePow
        (Iso.trans (Y :=
            Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
              ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor K₂ F))
            ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctorShift₂Iso
                K₂ F y :
              Iso (C := CochainComplex.{v_3, u_3, 0} D ℤ)
                ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor
                  (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F)
                (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                  ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor K₂
                    F)))
            (Iso.trans (Y :=
                Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                  (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
                    (K₁.mapBifunctor K₂ F)))
                (Functor.mapIso (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                    (K₁.mapBifunctorShift₁Iso K₂ F x) :
                  Iso (C := CochainComplex.{v_3, u_3, 0} D ℤ)
                    (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                      ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor
                        K₂ F))
                    (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                      (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
                        (K₁.mapBifunctor K₂ F))))
                (Iso.app (shiftFunctorComm (CochainComplex.{v_3, u_3, 0} D ℤ) x y) (K₁.mapBifunctor K₂ F) :
                  Iso (C := CochainComplex.{v_3, u_3, 0} D ℤ)
                    (Functor.obj
                      (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x ⋙
                        CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                      (K₁.mapBifunctor K₂ F))
                    (Functor.obj
                      (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y ⋙
                        CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
                      (K₁.mapBifunctor K₂ F))) :
              Iso (C := CochainComplex.{v_3, u_3, 0} D ℤ)
                (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                  ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor K₂
                    F))
                (Functor.obj
                  (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y ⋙
                    CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
                  (K₁.mapBifunctor K₂ F))) :
          Iso (C := CochainComplex.{v_3, u_3, 0} D ℤ)
            ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor
              (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F)
            (Functor.obj
              (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y ⋙
                CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
              (K₁.mapBifunctor K₂ F)))).hom
have w : CategoryStruct.comp (Y :=
    Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
      (K₁.mapBifunctor (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F))
    (CategoryStruct.comp (Y :=
        HomologicalComplex₂.total
          (Functor.obj (HomologicalComplex₂.shiftFunctor₁ D x)
            (Functor.obj (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁)
              (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂)))
          (ComplexShape.up ℤ))
        (HomologicalComplex₂.total.map
            (Iso.hom
              (K₁.mapBifunctorHomologicalComplexShift₁Iso
                (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F x))
            (ComplexShape.up ℤ) :
          Quiver.Hom (V := HomologicalComplex.{v_3, u_3, 0} D (ComplexShape.up ℤ))
            (HomologicalComplex₂.total
              (Functor.obj
                (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ))
                  (Functor.obj (CategoryTheory.shiftFunctor (HomologicalComplex.{v_1, u_1, 0} C₁ (ComplexShape.up ℤ)) x)
                    K₁))
                (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂))
              (ComplexShape.up ℤ))
            (HomologicalComplex₂.total
              (Functor.obj (HomologicalComplex₂.shiftFunctor₁ D x)
                (Functor.obj (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁)
                  (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂)))
              (ComplexShape.up ℤ)))
        (Iso.hom
            (HomologicalComplex₂.totalShift₁Iso
              (Functor.obj (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁)
                (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂))
              x) :
          Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
            (HomologicalComplex₂.total
              (Functor.obj (HomologicalComplex₂.shiftFunctor₁ D x)
                (Functor.obj (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁)
                  (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂)))
              (ComplexShape.up ℤ))
            (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
              (K₁.mapBifunctor (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂)
                F))) :
      Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
        ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor
          (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F)
        (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
          (K₁.mapBifunctor (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F)))
    (CategoryTheory.Functor.map (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
        (CategoryStruct.comp (Y :=
          HomologicalComplex₂.total
            (Functor.obj (HomologicalComplex₂.shiftFunctor₂ D y)
              (Functor.obj (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁)
                K₂))
            (ComplexShape.up ℤ))
          (HomologicalComplex₂.total.map (Iso.hom (K₁.mapBifunctorHomologicalComplexShift₂Iso K₂ F y))
              (ComplexShape.up ℤ) :
            Quiver.Hom (V := HomologicalComplex.{v_3, u_3, 0} D (ComplexShape.up ℤ))
              (HomologicalComplex₂.total
                (Functor.obj (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁)
                  (Functor.obj (CategoryTheory.shiftFunctor (HomologicalComplex.{v_2, u_2, 0} C₂ (ComplexShape.up ℤ)) y)
                    K₂))
                (ComplexShape.up ℤ))
              (HomologicalComplex₂.total
                (Functor.obj (HomologicalComplex₂.shiftFunctor₂ D y)
                  (Functor.obj
                    (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁) K₂))
                (ComplexShape.up ℤ)))
          (Iso.hom
              (HomologicalComplex₂.totalShift₂Iso
                (Functor.obj (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁)
                  K₂)
                y) :
            Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
              (HomologicalComplex₂.total
                (Functor.obj (HomologicalComplex₂.shiftFunctor₂ D y)
                  (Functor.obj
                    (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁) K₂))
                (ComplexShape.up ℤ))
              (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                (K₁.mapBifunctor K₂ F)))) :
      Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
        (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
          (K₁.mapBifunctor (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F))
        (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
          (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y) (K₁.mapBifunctor K₂ F)))) =
  HSMul.hSMul (β :=
    Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
      ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor
        (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F)
      (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
        (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y) (K₁.mapBifunctor K₂ F))))
    (x * y).negOnePow
    (CategoryStruct.comp (Y :=
        Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
          ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor K₂ F))
        (CategoryStruct.comp (Y :=
            HomologicalComplex₂.total
              (Functor.obj (HomologicalComplex₂.shiftFunctor₂ D y)
                (Functor.obj
                  (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ))
                    (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁))
                  K₂))
              (ComplexShape.up ℤ))
            (HomologicalComplex₂.total.map
                (Iso.hom
                  ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x)
                        K₁).mapBifunctorHomologicalComplexShift₂Iso
                    K₂ F y))
                (ComplexShape.up ℤ) :
              Quiver.Hom (V := HomologicalComplex.{v_3, u_3, 0} D (ComplexShape.up ℤ))
                (HomologicalComplex₂.total
                  (Functor.obj
                    (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ))
                      (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁))
                    (Functor.obj
                      (CategoryTheory.shiftFunctor (HomologicalComplex.{v_2, u_2, 0} C₂ (ComplexShape.up ℤ)) y) K₂))
                  (ComplexShape.up ℤ))
                (HomologicalComplex₂.total
                  (Functor.obj (HomologicalComplex₂.shiftFunctor₂ D y)
                    (Functor.obj
                      (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ))
                        (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁))
                      K₂))
                  (ComplexShape.up ℤ)))
            (Iso.hom
                (HomologicalComplex₂.totalShift₂Iso
                  (Functor.obj
                    (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ))
                      (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁))
                    K₂)
                  y) :
              Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
                (HomologicalComplex₂.total
                  (Functor.obj (HomologicalComplex₂.shiftFunctor₂ D y)
                    (Functor.obj
                      (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ))
                        (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁))
                      K₂))
                  (ComplexShape.up ℤ))
                (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                  ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor K₂
                    F))) :
          Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
            ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor
              (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F)
            (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
              ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor K₂ F)))
        (CategoryStruct.comp (Y :=
            Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
              (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x) (K₁.mapBifunctor K₂ F)))
            (CategoryTheory.Functor.map (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                (CategoryStruct.comp (Y :=
                  HomologicalComplex₂.total
                    (Functor.obj (HomologicalComplex₂.shiftFunctor₁ D x)
                      (Functor.obj
                        (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁) K₂))
                    (ComplexShape.up ℤ))
                  (HomologicalComplex₂.total.map (Iso.hom (K₁.mapBifunctorHomologicalComplexShift₁Iso K₂ F x))
                      (ComplexShape.up ℤ) :
                    Quiver.Hom (V := HomologicalComplex.{v_3, u_3, 0} D (ComplexShape.up ℤ))
                      (HomologicalComplex₂.total
                        (Functor.obj
                          (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ))
                            (Functor.obj
                              (CategoryTheory.shiftFunctor (HomologicalComplex.{v_1, u_1, 0} C₁ (ComplexShape.up ℤ)) x)
                              K₁))
                          K₂)
                        (ComplexShape.up ℤ))
                      (HomologicalComplex₂.total
                        (Functor.obj (HomologicalComplex₂.shiftFunctor₁ D x)
                          (Functor.obj
                            (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁)
                            K₂))
                        (ComplexShape.up ℤ)))
                  (Iso.hom
                      (HomologicalComplex₂.totalShift₁Iso
                        (Functor.obj
                          (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁)
                          K₂)
                        x) :
                    Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
                      (HomologicalComplex₂.total
                        (Functor.obj (HomologicalComplex₂.shiftFunctor₁ D x)
                          (Functor.obj
                            (Functor.obj (F.mapBifunctorHomologicalComplex (ComplexShape.up ℤ) (ComplexShape.up ℤ)) K₁)
                            K₂))
                        (ComplexShape.up ℤ))
                      (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
                        (K₁.mapBifunctor K₂ F)))) :
              Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
                (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                  ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor K₂
                    F))
                (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                  (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
                    (K₁.mapBifunctor K₂ F))))
            (NatTrans.app (Iso.hom (shiftFunctorComm (CochainComplex.{v_3, u_3, 0} D ℤ) x y)) (K₁.mapBifunctor K₂ F) :
              Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
                (Functor.obj
                  (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x ⋙
                    CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                  (K₁.mapBifunctor K₂ F))
                (Functor.obj
                  (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y ⋙
                    CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
                  (K₁.mapBifunctor K₂ F))) :
          Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
            (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
              ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor K₂ F))
            (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
              (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y)
                (K₁.mapBifunctor K₂ F)))) :
      Quiver.Hom (V := CochainComplex.{v_3, u_3, 0} D ℤ)
        ((Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_1, u_1, 0} C₁ ℤ) x) K₁).mapBifunctor
          (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_2, u_2, 0} C₂ ℤ) y) K₂) F)
        (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) x)
          (Functor.obj (CategoryTheory.shiftFunctor (CochainComplex.{v_3, u_3, 0} D ℤ) y) (K₁.mapBifunctor K₂ F))))
Tactic: dsimp [mapBifunctorShift₁Iso, mapBifunctorShift₂Iso]