class_docstr: `SBU Captioned Photo <http://www.cs.virginia.edu/~vicente/sbucaptions/>`_ Dataset.
  
  Args:
      root (string): Root directory of dataset where tarball
          ``SBUCaptionedPhotoDataset.tar.gz`` exists.
      transform (callable, optional): A function/transform that takes in a PIL image
          and returns a transformed version. E.g, ``transforms.RandomCrop``
      target_transform (callable, optional): A function/transform that takes in the
          target and transforms it.
      download (bool, optional): If True, downloads the dataset from the internet and
          puts it in root directory. If dataset is already downloaded, it is not
          downloaded again.
docstr: The number of photos in the dataset.
code: def __len__(self) -> int:
      """The number of photos in the dataset."""
      return len(self.photos)
  
file_path: vision/torchvision/datasets/sbu.py
imports: import os
  from typing import Any, Callable, Optional, Tuple
  from PIL import Image
  from .utils import check_integrity, download_and_extract_archive, download_url
  from .vision import VisionDataset
label_desc: Use image node_id 3 for calling the SBU obj's underlying member method code with example usage: obj.__len__() and returns: len