3 failures:
  @6 (⟨1, 6⟩): expected ')'
    ""
  @6 (⟨1, 6⟩): expected ':='
    ""
  @6 (⟨1, 6⟩): unexpected end of input
    ""

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