class_docstr: Iterable DataLoader Object
      
code: def __iter__(self):
      if isinstance(self.dataset, StreamDataset):
          if self.stream_shuffle_size > 0:
              data_generator = self._stream_shuffle_data_generator
          else:
              data_generator = self._streamdata_generator
      else:
          data_generator = self._data_generator
  
      for batch_data in data_generator():
          yield batch_data
  
imports: import warnings
  import time
  import numpy
  from collections import namedtuple
  import paddle
  from pgl.utils import mp_reader
  from pgl.utils.data.dataset import Dataset, StreamDataset
  from pgl.utils.data.sampler import Sampler, StreamSampler
label_desc: Use image node_id 5 for calling the _DataLoaderIter obj's underlying member method code with example usage: obj.__iter__() without return types