code: function addPlacement(request) {
    const placementInfo = {
      placement_id: request.adUnitCode,
      callback_id: request.bidId,
      sizes: request.sizes
    }
    if (request.params && request.params.placementId) {
      placementInfo.ym_placement_id = request.params.placementId
    }
    return JSON.stringify(placementInfo);
  }
docs: *************************************
  Helper Functions
  ************************************* 
  Adds placement information to array
  @param request bid request