title: Strange line in django_cron
body: <p>I'm using this instruction <a href="http://django-cron.readthedocs.org/en/latest/installation.html" rel="nofollow">http://django-cron.readthedocs.org/en/latest/installation.html</a> and can't understand meaning of "a unique code" line. </p>
  
  <pre><code>from django_cron import CronJobBase, Schedule
  
  class MyCronJob(CronJobBase):
      RUN_EVERY_MINS = 120 # every 2 hours
  
      schedule = Schedule(run_every_mins=RUN_EVERY_MINS)
      code = 'my_app.my_cron_job'    # a unique code
  
      def do(self):
          pass    # do your thing here
  </code></pre>
  
  <p>Can anyone explain me what this line do?</p>
  
  <pre><code>code = 'my_app.my_cron_job'    # a unique code
  </code></pre>