def digestable_hash
      @item.slice(CLASS_KEY, QUEUE_KEY, UNIQUE_ARGS_KEY).tap do |hash|
        hash.delete(QUEUE_KEY) if unique_across_queues?
        hash.delete(CLASS_KEY) if unique_across_workers?
      end
    end
def digestable_hash
      @item.slice(CLASS_KEY, QUEUE_KEY, UNIQUE_ARGS_KEY).tap do |hash|
        hash.delete(QUEUE_KEY) if unique_across_queues?
        hash.delete(CLASS_KEY) if unique_across_workers?
      end
    end
Filter a hash to use for digest
 @return [Hash] to use for digest