code: function highlight (code, lang) {
    if (!lang) {
      return code
    }
  
    var isDiff = DIFF_REGEXP.test(lang)
  
    // Remove the diff suffix. E.g. "javascript.diff".
    lang = lang.replace(DIFF_REGEXP, '')
  
    // Ignore unknown languages.
    if (!isDiff && !supported(lang)) {
      return code
    }
  
    return isDiff ? diff(code, lang) : hljs.highlight(lang, code).value
  }
docs: Syntax highlighting in the format Marked supports.
  
  @param  {String} code
  @param  {String} lang
  @return {String}