code: def _get_batch_fmtstr(self, num_batches):
      num_digits = len(str(num_batches // 1))
      fmt = "{:" + str(num_digits) + "d}"
      return "[" + fmt + "/" + fmt.format(num_batches) + "]"
  
imports: import collections
  import torch
  from torch import Tensor
  import torch.nn
  import torch.backends.cudnn
  import subprocess
  import os
  import time
  import shutil
  from datetime import datetime
  import torch.optim
  from torch.optim import lr_scheduler
  import sys
  import models
  import numpy
  import torch.nn
  import math
label_desc: Use image node_id 3 for calling the ProgressMeter obj's underlying member method code with example usage: obj._get_batch_fmtstr(num_batches) and returns: unknown