docs: def _job_handler(self) -> bool:
          """Process the work items."""
          while True:
              try:
                  task = self._unfullfilled.get_nowait()
              except queue.Empty:
                  break
              else:
                  self._log.debug("Job: %s" % str(task))
                  engine = self._dyn_loader(task['engine'], task)
                  task['start_time'] = now_time()
                  results = engine.search()
                  task['end_time'] = now_time()
                  duration: str = str((task['end_time'] - task['start_time']).seconds)
                  task['duration'] = duration
                  task.update({'results': results})
                  self._fulfilled.put(task)
          return True