code: def size(self):
      return len(self.annotations)
  
imports: import csv
  import json
  import os
  import warnings
  import numpy
  from PIL import Image
  from .generator import Generator
  from ..utils.image import read_image_bgr
label_desc: Use image node_id 3 for calling the OpenImagesGenerator obj's underlying member method code with example usage: obj.size() and returns: len