query-maas.py

#!/usr/bin/env python

import requests_oauthlib 

url =  'http://10.0.0.205/MAAS'
mac_url = '{}/api/2.0/machines/?format=json'.format(url)
api_key = 'YOUR MAAS API KEY'
_keys = api_key.split(':')
consumer_key = _keys[0]
access_token = _keys[1]
token_secret = _keys[2]

maas_session = requests_oauthlib.OAuth1Session(
    consumer_key,
    signature_method='PLAINTEXT',
    resource_owner_key=access_token,
    resource_owner_secret=token_secret)
print(maas_session.get(mac_url).text)

Works out of the box and is IMHO much better (smaller & easier to understand) than the original MAAS API documentation.
Thanks!

BTW: the ?format=json does not work nowadays. Instead you need to pass in the HTTP Accept header (like application/x-yaml or even application/python-pickle)