code: def reward_accuracy(output, target, topk=(1,)):
      batch_size = target.size(0)
      _, predicted = torch.max(output.data, 1)
      return (predicted == target).sum().item() / batch_size
  
label_desc: Use image node_id 2 for calling a global function with example usage: reward_accuracy(output, target, topk) and returns: unknown