∀ {ι : Type u_1} {ι' : Type u_2} {c : ComplexShape ι} {c' : ComplexShape ι'} {C : Type u_3}
  [inst : CategoryTheory.Category.{v_1, u_3} C] [inst_1 : CategoryTheory.Limits.HasZeroMorphisms C]
  [inst_2 : CategoryTheory.Limits.HasZeroObject C] (K : HomologicalComplex C c) (e : c.Embedding c') {i j k : ι}
  {i' j' k' : ι'} (hj' : e.f j = j') (hi : c.prev j = i) (hi' : c'.prev j' = i') (hk : c.next j = k)
  (hk' : c'.next j' = k') (h : (K.sc' i j k).HomologyData),
  (HomologicalComplex.extend.homologyData K e hj' hi hi' hk hk' h).left =
    HomologicalComplex.extend.leftHomologyData K e hj' hi hi' hk hk' h.left