class_docstr: PyTorch model operator base
docstr: For training model
code: def train(self):
      """
      For training model
      """
      pass
  
file_path: towhee/tests/unittests/mock_operators/pytorch_cnn_operator/pytorch_cnn_operator.py
imports: from typing import NamedTuple
  import numpy
  import torch
  import torchvision
  from towhee.operator import Operator
label_desc: Use image node_id 3 for calling the PytorchCnnOperator obj's underlying member method code with example usage: obj.train() without return types