---- after assert ----
a : ℕ
⊢ ℕ

a : ℕ,
x : ℕ := ?m_1
⊢ a = a
--- inside focus tac ---
a : ℕ
⊢ ℕ
focus_tac.lean:4:3: error: focus tactic failed, focused goal has not been solved
state:
a : ℕ
⊢ ℕ
---- after assert ----
a : ℕ
⊢ ℕ

a : ℕ,
x : ℕ := ?m_1
⊢ a = a
--- inside focus tac ---
a : ℕ
⊢ ℕ
---- after focus tac ----
a : ℕ,
x : ℕ := a
⊢ a = a