Failure @16 (⟨1, 16⟩): '_'
Final stack:
  [(Lean.Doc.Syntax.para
    "para{"
    [(Lean.Doc.Syntax.bold
      "*"
      [(Lean.Doc.Syntax.text (str "\"This is \""))
       (Lean.Doc.Syntax.emph
        "_"
        [(Lean.Doc.Syntax.text
          (str "\"strong\""))]
        <missing>)]
      "*")
     (Lean.Doc.Syntax.text
      (str "\" not regular\""))]
    "}")]
Remaining: "* not regular_ emphasis"