class_docstr: Dataset that provides keyframes for a set of videos.
class_docstr_tok: ["Dataset","that","provides","keyframes","for","a","set","of","videos","."]
code: def __len__(self):
      return len(self.video_list)
  
file_path: detectron2/projects/DensePose/densepose/data/video/video_keyframe_dataset.py
imports: import csv
  import logging
  import numpy
  from typing import Any, Callable, Dict, List, Optional, Union
  import av
  import torch
  from torch.utils.data.dataset import Dataset
  from detectron2.utils.file_io import PathManager
  from ..utils import maybe_prepend_base_path
  from .frame_selector import FrameSelector, FrameTsList
label_desc: Use image node_id 3 for calling the VideoKeyframeDataset obj's underlying member method code with example usage: obj.__len__() and returns: len