code: def __len__(self):
      return self.indexed_dataset.sequence_lengths.shape[0]
  
file_path: megatron-lm/megatron/data/multimodal_dataset.py
imports: from PIL import Image, UnidentifiedImageError
  import numpy
  import io
  import torch
  from torchvision.transforms import Compose, ToTensor, Normalize, ToPILImage, RandomResizedCrop, Resize
label_desc: Use image node_id 2 for calling the MultiModalDataset obj's underlying member method code with example usage: obj.__len__() and returns: self