code: def __len__(self):
      return len(self.valid_person_list)
  
file_path: deep-learning-for-image-processing/pytorch_keypoint/HRNet/my_dataset_coco.py
imports: import os
  import copy
  import torch
  import numpy
  import cv2
  import torch.utils.data
  from pycocotools.coco import COCO
label_desc: Use image node_id 3 for calling the CocoKeypoint obj's underlying member method code with example usage: obj.__len__() and returns: len