have := Iff.mpr Nat.not_odd_iff_even this
case h
n : Nat
h : n > 0
a✝ : Odd n
h' : ¬Even (n - 1)
this✝ : Odd (n - 1)
this : Even n
⊢ False
case h
n : Nat
h : n > 0
a✝ : Odd n
h' : ¬Even (n - 1)
this✝¹ : Odd (n - 1)
this✝ : Even n
this : ¬Odd n
⊢ False