'finish a task based on task_name, call queue.task_done()'

def finish_a_task(self, task_name):

    if (task_name == TPEnum.URL_FETCH):
        self._fetch_queue.task_done()
    elif (task_name == TPEnum.HTM_PARSE):
        self._parse_queue.task_done()
    elif (task_name == TPEnum.ITEM_SAVE):
        self._save_queue.task_done()
    self.update_number_dict(TPEnum.TASKS_RUNNING, (-1))
    return
