anchor.diff:    <USER ID>, {
       'targetEntityType' => 'item',
       'targetEntityId' => <ITEM ID>
  +  }
  +)
  +
  +# Set a list of unavailable items
  +client.create_event(
  +  '$set',
  +  'constraint',
  +  'unavailableItems', {
  +    'properties' => { 'items' => ['<ITEM ID1>', '<ITEM ID2>'] }
     }
   )
   
  
positive.code:     .targetEntityId(<ITEM_ID>);
  client.createEvent(viewEvent);
  
  ```
    </div>
    <div data-tab="REST API" data-lang="json">
  
negative.code: {"itemScores":[{"item":"i33","score":0.005999267822052033},{"item":"i5","score":0.002848917309942939},{"item":"i2","score":0.002848917309942939},{"item":"i7","score":0.0017118948432933486}]}
  ```
  
  INFO: You should send a full list of unavailable items whenever there is any updates in the list.
  
  When there is no more unavilable items, simply set an empty list. ie.
  
  