code: def __call__(self, extension, data):
      if extension != "mat":
          return None
      with io.BytesIO(data) as stream:
          return self.sio.loadmat(stream, **self.loadmat_kwargs)
  
imports: import io
  import json
  import os.path
  import pickle
  import tempfile
  import torch
  from torch.utils.data.datapipes.utils.common import StreamWrapper
label_desc: Use image node_id 2 for calling the MatHandler obj's underlying member method code with example usage: obj.__call__(extension, data) and returns: None, self