pan id of the span in the process
  dictionary in a tuple.</td></tr>
<tr><td valign="top"><a href="#log-1">log/1</a></td><td>Add a log to the span in the process dictionary.</td></tr>
<tr><td valign="top"><a href="#log-2">log/2</a></td><td>Add a log with specific service to the span in the process
  dictionary.</td></tr>
<tr><td valign="top"><a href="#put_span-1">put_span/1</a></td><td>Put a span to the process dictionary.</td></tr>
<tr><td valign="top"><a href="#start-1">start/1</a></td><td>start a new spa