unable to set consumer group

[Ilja Golshtein]

Hello.

I am trying to create consumer using kafka_python-0.9.5.

I expect that several instances of the script

==
consumer = KafkaConsumer('some-topic',
                         auto_offset_reset='largest',
                         metadata_broker_list=['localhost:9092'],
                         group_id='vasya_group',
                         auto_commit_enable=True)
consumer.set_topic_partitions('some-topic')
while True:
    msg=consumer.next()
    print(msg)
==
would receive different messages, while in reality every instance receives all 
messages.

What can be done to achieve 
"Consumers label themselves with a consumer group name, and each message 
published to a topic is delivered to one consumer instance within each 
subscribing consumer group" as advertised in Kafka Documentation?

I am 100% that messages are distributed among several partitions (namely 10).

Thanks.

-- 
Best regards
Ilja Golshtein