How to use the memorious.core.conn.get function in memorious

def load_session(self):
        if self.STATE_SESSION not in self.context.state:
            return
        key = self.context.state.get(self.STATE_SESSION)
        value = conn.get(key)
        if value is not None:
            session = codecs.decode(bytes(value, 'utf-8'), 'base64')
            return pickle.loads(session)

def last_run(cls, crawler):
        last_run = conn.get(make_key(crawler, "last_run"))
        return unpack_datetime(last_run)

def runs(cls, crawler):
        runs = []
        for run_id in cls.run_ids(crawler):
            start = conn.get(make_key("run", run_id, "start"))
            end = conn.get(make_key("run", run_id, "end"))
            total_ops = conn.get(make_key("run", run_id, "total_ops"))
            runs.append({
                'run_id': run_id,
                'total_ops': unpack_int(total_ops),
                'start': unpack_datetime(start, datetime.utcnow()),
                'end': unpack_datetime(end)
            })
        return runs

def runs(cls, crawler):
        runs = []
        for run_id in cls.run_ids(crawler):
            start = conn.get(make_key("run", run_id, "start"))
            end = conn.get(make_key("run", run_id, "end"))
            total_ops = conn.get(make_key("run", run_id, "total_ops"))
            runs.append({
                'run_id': run_id,
                'total_ops': unpack_int(total_ops),
                'start': unpack_datetime(start, datetime.utcnow()),
                'end': unpack_datetime(end)
            })
        return runs

def op_count(cls, crawler, stage=None):
        """Total operations performed for this crawler"""
        if stage:
            total_ops = conn.get(make_key(crawler, stage))
        else:
            total_ops = conn.get(make_key(crawler, "total_ops"))
        return unpack_int(total_ops)

def get_tag(self, key):
        value = conn.get(make_key(self.crawler, "tag", key))
        if value is not None:
            return load_json(value)

def runs(cls, crawler):
        runs = []
        for run_id in cls.run_ids(crawler):
            start = conn.get(make_key("run", run_id, "start"))
            end = conn.get(make_key("run", run_id, "end"))
            total_ops = conn.get(make_key("run", run_id, "total_ops"))
            runs.append({
                'run_id': run_id,
                'total_ops': unpack_int(total_ops),
                'start': unpack_datetime(start, datetime.utcnow()),
                'end': unpack_datetime(end)
            })
        return runs

def latest_runid(cls, crawler):
        return conn.get(make_key(crawler, "current_run"))