code: def __len__(self):
      return len(self.x)
  
file_path: fastNLP/tests/helpers/datasets/paddle_data.py
imports: import numpy
  from fastNLP.envs.imports import _NEED_IMPORT_PADDLE
label_desc: Use image node_id 2 for calling the PaddleArgMaxDataset obj's underlying member method code with example usage: obj.__len__() and returns: len