{M : Type u_1} →
  [inst : AddMonoid M] →
    {p : M} →
      {motive : AddIrreducible p → Sort u} →
        (t : AddIrreducible p) →
          ((not_isAddUnit : ¬IsAddUnit p) →
              (isAddUnit_or_isAddUnit : ∀ ⦃a b : M⦄, p = a + b → IsAddUnit a ∨ IsAddUnit b) → motive ⋯) →
            motive t