revert p
ℕ : Type
inst✝¹ : Natural ℕ
ℤ : Type
inst✝ : Integer ℤ
p q : Fraction ℤ
⊢ Positive p.denominator → Positive q.denominator → Positive (p + q).denominator
ℕ : Type
inst✝¹ : Natural ℕ
ℤ : Type
inst✝ : Integer ℤ
q : Fraction ℤ
⊢ ∀ {p : Fraction ℤ}, Positive p.denominator → Positive q.denominator → Positive (p + q).denominator