convert (pair_perm' w a _).symm
n d : ℕ
inst✝ : NeZero d
w a : Weight n d
i j : Fin (Nat.succ n)
⊢ pair w (Weight.comp a (Equiv.swap i j)) = pair (Weight.comp w (Equiv.swap i j)) a
case h.e'_2.h.e'_4.h.e'_4
n d : ℕ
inst✝ : NeZero d
w a : Weight n d
i j : Fin (Nat.succ n)
⊢ Equiv.swap i j = (Equiv.swap i j)⁻¹