(1) First of all, simply try to run:
        python send_sensor_data.py --speedFactor=30

    If this fails, look at your error.  Is it because a module could not be found
    or is it because the pubsub module has no attribute named 'Client'?

(2) If this fails because google.cloud.pubsub can not be found, then do:
        sudo pip install google-cloud-pubsub
    Then, try again

(3) If you get a failure that the module pubsub has no attribute called Client
    then you are either:
    - running into path problems because an older version of pub/sub is installed on your machine
    - trying to use a newer version of pub/sub

    The solution is to use virtualenv:

    (a) virtualenv cpb104
    (b) source cpb104/bin/activate
    (c) pip install google-cloud-pubsub==0.27.0
    (d) gcloud auth application-default login

    Then, try the send_sensor_data.py again

    To exit the virtualenv environment, type 'deactivate'