ebug session
                </li>
</ul></div>
          </li>
</ul></div>
<p>
        We can see from the scheme above that reproduction of an error is <span class="emphasis"><em>costly</em></span>,
        since usually one tends to reproduce the error, which in turn induces at
        least the compilation of the test module. Also, a hidden cost is the lookup
        at the line of code that contains the failing statement, which triggers a
        sequence of back and forth lookup between the log on one 