have : compare n m = Ordering.eq := Natural.compare_eq.mpr this
ℕ : Type
inst✝ : Natural ℕ
n m : ℕ
x✝ : n——m ≃ 0
this : n ≃ m
⊢ (n——m).sgn ≃ 0
ℕ : Type
inst✝ : Natural ℕ
n m : ℕ
x✝ : n——m ≃ 0
this✝ : n ≃ m
this : compare n m = Ordering.eq
⊢ (n——m).sgn ≃ 0