anchor.diff:  ### Input Query
   
   - User entity ID
  -- Num of items to be recommended
  +- Number of items to be recommended
   - List of whitelisted item categories (optional)
   - List of whitelisted item entity IDs (optional)
   - List of blacklisted item entity IDs (optional)
  
positive.code: ```
  $ curl -H "Content-Type: application/json" \
  -d '{
    "user": "u1",
    "num": 4,
    "blackList": ["i21", "i26", "i40"]
  }' \
  http://localhost:8000/queries.json
  
negative.code: 
  ## 6. Use the Engine
  
  Now, You can retrieve predicted results. To recommend 4 items to user ID "u1". You send this JSON `{ "userEntityId": "u1", "number": 4 }` to the deployed engine and it will return a JSON of the recommended items. Simply send a query by making a HTTP request or through the `EngineClient` of an SDK.
  
  With the deployed engine running, open another temrinal and run the following `curl` command or use SDK to send the query:
  
  