How to use the memorious.core.manager function in memorious

def get_crawler(name):
    crawler = manager.get(name)
    if crawler is None:
        abort(404)
    return crawler

def get_crawler(name):
    crawler = manager.get(name)
    if crawler is None:
        msg = 'Crawler [%s] not found.' % name
        raise click.BadParameter(msg, param=crawler)
    return crawler

def get_crawler(name):
    return manager.get(name)

def get_stages(self):
        return list({str(stage) for _, stage in manager.stages})

def from_state(cls, state, stage):
        state_crawler = state.get('crawler')
        crawler = manager.get(state_crawler)
        if crawler is None:
            raise RuntimeError("Missing crawler: [%s]" % state_crawler)
        stage = crawler.get(stage)
        if stage is None:
            raise RuntimeError('[%r] has no stage: %s' % (crawler, stage))
        return cls(crawler, stage, state)

def context():
    return {
        'version': settings.VERSION,
        'num_crawlers': len(manager),
        'state_change': state_change
    }

def run_cleanup():
    manager.run_cleanup()