code: function(exception, options = {}) {
          const html = formatExceptionLines(exception, options, function({ line, type }) {
              line = escapeHtml(line);
  
              const style = options.inlineStyle
                  ? `style='${HTML_INLINE_STYLES[type] || ''}'`
                  : `class=${type}`;
  
              // Use inline styles, since email doesn't support style sheets.
              switch (type) {
                  case HEADER:
                      return `<h2 ${style}>${line}</h2>`;
                  default:
                      return `<span ${style}>${line}</span><br />`;
              }
          });
  
          const style = options.inlineStyle ? "style='font-family: monospace'" : "class='exception'";
          return `<div ${style}>${html}</div>`;
      }
docs: Format an exception as HTML.  If `options.inlineStyle` is true, this will use inline styling for each line. Otherwise each line will be given a CSS class ('hedaer', 'source', 'our-source', 'divider', 'unknown').  Note that email generally will ignore CSS, so if you're emailing this exception, inline stlying is a must.