import json
from watson_developer_cloud import ConversationV1

conversation = ConversationV1(
    username='SERVICE_USERNAME',
    password='SERVICE_PASSWORD',
    version='2016-07-11')

workspace_id = 'WORKSPACE_ID_CONVERSATION'

response = conversation.message(workspace_id=workspace_id, context= {'username':'Simon'})

print json.dumps(response)

{
  "entities":[],
  "intents":[],
  "output":{
    "log_messages":[],
    "nodes_visited":["node_1_1472298724972],
    "text":["Hello Simon"]
  },
  "context":{
    "username":"Simon",
    "conversation_id":"9dc1501b-ac53-4b51-a299-37f5314ebf89",
    "system":{
      "dialog_turn_counter":1,
      "dialog_stack":["root"],
      "dialog_request_counter":1
    }
  },
  "input":{}
}