Added handling of hidden jobs.

        exported = {}

        for key, val in self.iteritems():

            if key.startswith('_'):

                continue

            if isinstance(val, datetime):

                now = datetime.now()

                dt = now - val

        '''

        for job in self._jobs.itervalues():

            if done is not None and job['done'] != done:

                continue

            else:

            if (done is None or job['done'] == done) and not job.get('_hidden'):

                yield job