errors.lean:4:0: error: unknown identifier 'a'
tst1 : nat → nat → nat
errors.lean:12:2: error: function expected at
  tactic.cases [tactic.expr add] tactic.expr_list.nil
errors.lean:22:12: error: unknown identifier 'b'
tst3 : A → A → A
foo.tst1 : ℕ → ℕ → ℕ
foo.tst2 : ℕ → ℕ → ℕ
foo.tst3 : Π (A : Type), A → A → A