code: function enclose(title) {
    var delimiter =
      title.indexOf(quotationMark) === -1 ? quotationMark : apostrophe
    return delimiter + title + delimiter
  }
docs: There is currently no way to support nested delimiters across Markdown.pl, CommonMark, and GitHub (RedCarpet).  The following code supports Markdown.pl and GitHub. CommonMark is not supported when mixing double- and single quotes inside a title.