code: def __len__(self):
      return len(self.base)
  
file_path: chainer/chainerx_cc/examples/imagenet_py/image_dataset.py
imports: import random
  import chainer
  import numpy
label_desc: Use image node_id 2 for calling the PreprocessedDataset obj's underlying member method code with example usage: obj.__len__() and returns: len