4 failures:
  @4 (⟨1, 4⟩): expected ')'
    ""
  @4 (⟨1, 4⟩): expected ':='
    ""
  @4 (⟨1, 4⟩): expected token
    ""
  @4 (⟨1, 4⟩): unexpected end of input
    ""

Final stack:
  (Lean.Doc.Syntax.named
   "("
   <missing>
   <missing>
   <missing>
   <missing>)