code: def __len__(self):
      return self.length
  
file_path: ColossalAI/examples/tutorial/large_batch_optimizer/train.py
imports: import torch
  import torch.nn
  from torchvision.models import resnet18
  from tqdm import tqdm
  import colossalai
  from colossalai.legacy.core import global_context
  from colossalai.logging import get_dist_logger
  from colossalai.nn.lr_scheduler import CosineAnnealingWarmupLR
  from colossalai.nn.optimizer import Lamb, Lars
label_desc: Use image node_id 5 for calling the DummyDataloader obj's underlying member method code with example usage: obj.__len__() and returns: self