refine (lt_mem_nhds (show (x : ℕ∞) < ⊤ from WithTop.coe_lt_top x)).prod_nhds ?_
b : ℕ∞
ha : ⊤ ≠ 0 ∨ b ≠ ⊤
hb : b ≠ 0 ∨ ⊤ ≠ ⊤
h : b ≤ ⊤
x : ℕ
⊢ ∀ᶠ (c : ℕ∞ × ℕ∞) in 𝓝 (⊤, b), ↑x < c.1 ∧ 0 < c.2
b : ℕ∞
ha : ⊤ ≠ 0 ∨ b ≠ ⊤
hb : b ≠ 0 ∨ ⊤ ≠ ⊤
h : b ≤ ⊤
x : ℕ
⊢ ∀ᶠ (y : ℕ∞) in 𝓝 b, 0 < y