code: def GetFeedItemIdsForCampaign(campaign_feed):
    
    feed_item_ids = set()
  
    try:
      lhs_operand = campaign_feed['matchingFunction']['lhsOperand']
    except KeyError:
      lhs_operand = None
  
    if (lhs_operand and lhs_operand[0]['FunctionArgumentOperand.Type'] ==
        'RequestContextOperand'):
      request_context_operand = lhs_operand[0]
  
      if (request_context_operand['contextType'] == 'FEED_ITEM_ID' and
          campaign_feed['matchingFunction']['operator'] == 'IN'):
        for argument in campaign_feed['matchingFunction']['rhsOperand']:
          if argument['xsi_type'] == 'ConstantOperand':
            feed_item_ids.add(argument['longValue'])
  
    return feed_item_ids
docs: Gets the Feed Item Ids used by a campaign through a given Campaign Feed.
  
    Args:
      campaign_feed: the Campaign Feed we are retrieving Feed Item Ids from.
  
    Returns:
      A list of Feed Item IDs.