<div class="frame" id="frame-$frame.id">
  <h4>File <cite class="filename">"$escape(frame.filename)"</cite>,
      line <em class="line">$frame.lineno</em>,
      in <code class="function">$escape(frame.function_name)</code></h4>
  <pre>${escape(frame.current_line.strip())}</pre>
</div>
