conn.rpush('lkey', 1, 2, 3)
conn.lpush('lkey', 1, 2, 3)
conn.lpop('lkey')
conn.rpop('lkey')
conn.lrange('lkey', 0, -1) # return a list
conn.lindex('lkey', 2)
conn.ltrim('lkey', 1, -1)
conn.blpop(['list1', 'list2'], 1)
conn.brpop(['list1', 'list2'], 2)
conn.rpoplpush('list1', 'list2')
conn.brpoplpush('list1', 'list2', 3)
# set
conn.sadd('key', 'item1', 'item2')
conn.srem('key', 'item2')
conn.ismember('key', 'item') # not sure
conn.scard('key')
conn.smembers('key')
conn.smove('key1', 'key2', 'item')
conn.sdiff('key1', 'key2', 'key3') # 返回存在第一个集合，不在其他集合的元素
conn.sinter('key1', 'key2')
conn.sunion('key1', 'key2',)
# string
conn.set('key', '15')
conn.get('key')
conn.incr('key') # conn.incr('key', 1)
conn.incr('key', 5)
conn.decr('key', 5)
conn.incrbyfloat('key')
conn.incrbyfloat('key', -4.5)
