We currently have no Python lib written, but there are some integrations done in Python. To get you started you can for instance control your plug like this.
Install the mqtt-lib if not done already.
apt-get install python-paho-mqtt (or python3-paho-mqtt if you are using python3)
Then it is quite simple. If you do it on the Rasbperry that is connected to IoT Open you don't even need authentication since that is already taken care of. See this example:
import paho.mqtt.client as mqtt
client = mqtt.Client('python-1234')
client.connect('localhost')
client.publish('set/obj/test/1', '{"value": 255}')
Where set/obj/test/1is the topic_write for the plug. 255 is the value for on, and 0 is for off.
Please ask if you have more questions, but this should get you started.
