code: def test_v4(self):
      from paddle.io import DataLoader
      from fastNLP import Collator
      from paddle.io import Dataset
      import paddle
  
      class PaddleArgMaxDataset(Dataset):
          def __init__(self, num_samples, num_features):
              self.x = paddle.randn((num_samples, num_features))
              self.y = self.x.argmax(axis=-1)
  
          def __len__(self):
              return len(self.x)
  
          def __getitem__(self, item):
              return {"x": self.x[item], "y": self.y[item]}
  
      ds = PaddleArgMaxDataset(100, 2)
      dl = DataLoader(
          ds, places=None, collate_fn=Collator(), batch_size=4
      )
      for batch in dl:
          print(batch)
  
file_path: fastNLP/tests/core/dataloaders/paddle_dataloader/test_fdl.py
imports: import pytest
  import numpy
  from fastNLP.core.dataloaders.paddle_dataloader.fdl import PaddleDataLoader, prepare_paddle_dataloader
  from fastNLP.core.dataset import DataSet
  from fastNLP.io.data_bundle import DataBundle
  from fastNLP.core.log import logger
  from fastNLP.core.collators import Collator
  from fastNLP.envs.imports import _NEED_IMPORT_PADDLE
label_desc: Use image node_id 5 for calling the TestPaddle obj's underlying member method code with example usage: obj.test_v4() and returns: len, dict