intro (_ : n₁ ≃ n₂) (_ : Positive n₁)
ℕ : Type
inst✝³ : Core ℕ
inst✝² : Induction ℕ
inst✝¹ : Addition ℕ
inst✝ : Sign ℕ
n₁ n₂ : ℕ
⊢ n₁ ≃ n₂ → Positive n₁ → Positive n₂
ℕ : Type
inst✝³ : Core ℕ
inst✝² : Induction ℕ
inst✝¹ : Addition ℕ
inst✝ : Sign ℕ
n₁ n₂ : ℕ
x✝¹ : n₁ ≃ n₂
x✝ : Positive n₁
⊢ Positive n₂