2. OS type and version
   Any and all

3. Python version and virtual environment information python --version
   Python 3.6.3

4. google-cloud-python version pip show google-cloud, pip show google-<service> or pip freeze
   google==1.9.3
   google-api-core==0.1.1
   google-auth==1.2.1
   google-cloud-core==0.28.0
   google-cloud-pubsub==0.29.0
   google-gax==0.15.16
   googleapis-common-protos==1.5.3
   grpc-google-iam-v1==0.11.4

5. Stacktrace if available

6. Steps to reproduce
   Run example code for listing subscriptions for a topic from here:
   https://cloud.google.com/pubsub/docs/admin

7. Code example

def list_subscriptions_in_topic(project, topic_name):
    """Lists all subscriptions for a given topic."""
    subscriber = pubsub_v1.SubscriberClient()
    topic_path = subscriber.topic_path(project, topic_name)

    for subscription in subscriber.list_subscriptions(topic_path):
        print(subscription.name)

topic path being used as shown by topic_path = subscriber.topic_path(project, topic_name):
projects/my-team-dev/topics/testing-topic

Using GitHub flavored markdown can help make your request clearer.
See: https://guides.github.com/features/mastering-markdown/