something wrong when running Pulsar-ds example

[gas0189]

• pulsar version: 2.0.2
• python version: 3.6.3
• platform: Ubuntu

When I learn the Pulsar-ds example, something is wrong : the client.ping() does NOT return 'True', WHY?

Python 3.6.3 (default, Oct  3 2017, 21:45:48) 
[GCC 7.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from pulsar.apps.data import create_store
>>> store = create_store('pulsar://localhost:6410')
>>> client = store.client()
>>> client
RedisClient(pulsar://localhost:6410)
>>> client.ping()
<coroutine object RedisStore.execute at 0x7fea0700f678>

I'm sure the ds-server is OK:

Python 3.6.3 (default, Oct  3 2017, 21:45:48) 
[GCC 7.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from pulsar.apps.ds import PulsarDS
>>> pds = PulsarDS()
Python 3.6.3 (default, Oct  3 2017, 21:45:48) 
[GCC 7.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from pulsar.apps.ds import PulsarDS
>>> pds = PulsarDS()
>>> pds.version
'2.0.2'
>>> pds.start()
21:16:13 [p=3338, t=140539003582272, INFO, pulsar.arbiter] Booting
21:16:13 [p=3338, t=140539003582272, INFO, pulsar] mailbox serving on 127.0.0.1:41789
21:16:13 [p=3338, t=140539003582272, INFO, pulsar.pulsards] pulsards serving on 127.0.0.1:6410

Is that OK? How can I do for this?