set f := factorization' h
case intro
a b : ℤ√(-3)
h : IsCoprime a.re a.im
hmem : b ∈ factorization' h
h1 : a = Multiset.prod (factorization' h) ∨ a = -Multiset.prod (factorization' h)
⊢ IsCoprime b.re b.im
case intro
a b : ℤ√(-3)
h : IsCoprime a.re a.im
f : Multiset (ℤ√(-3)) := factorization' h
hmem : b ∈ f
h1 : a = Multiset.prod f ∨ a = -Multiset.prod f
⊢ IsCoprime b.re b.im