obtain rfl | rfl := hu' <;> apply dvd_mul_left
case intro.refine'_1
a : ℤ√(-3)
hcoprime : IsCoprime a.re a.im
heven : Even a.norm
u' : ℤ√(-3)
hu' : a = { re := 1, im := 1 } * u' ∨ a = { re := 1, im := -1 } * u'
⊢ u' ∣ a
no goals