code: def __len__(self):
      return len(self.images_path)
  
file_path: deep-learning-for-image-processing/pytorch_object_detection/mask_rcnn/my_dataset_voc.py
imports: import os
  import json
  from lxml import etree
  import numpy
  from PIL import Image
  import torch
  from torch.utils.data import Dataset
  from train_utils import convert_to_coco_api
label_desc: Use image node_id 4 for calling the VOCInstances obj's underlying member method code with example usage: obj.__len__() and returns: len