Python SDK Documentation could use example of upsert involving JSON text

I have a Python script that retrieves JSON documents from Google AppEngine and needs to upsert them into a Couchbase bucket. The documentation on 'upsert', found here:

https://developer.couchbase.com/documentation/server/current/sdk/python/start-using-sdk.html

provides an example of 'upsert' using Python objects, e.g., 

cb.upsert('u:king_arthur', {'name': 'Arthur', 'email': 'kingarthur@couchbase.com', 'interests': ['Holy Grail', 'African Swallows']})

The more detailed API documentation, found here:

http://pythonhosted.org/couchbase/api/couchbase.html

Also uses Python objects. But there is no example showing me what to do if I have a string of JSON. What I'd like to see is something like:

JSONstr = "{\"key1\": \"value1\", \"key2\": 123}"

JSONobj = json.loads(JSONstr)

cb.upsert("documentID",JSONobj)