code: def __iter__(self):
      while True:
          try:
              label_samples = next(self.label_loader_iter)
          except:
              self.label_loader_iter = iter(self.label_loader)
              label_samples = next(self.label_loader_iter)
  
          try:
              unlabel_samples = next(self.unlabel_loader_iter)
          except:
              self.unlabel_loader_iter = iter(self.unlabel_loader)
              unlabel_samples = next(self.unlabel_loader_iter)
  
          yield (
              label_samples[0],  # sup weak
              label_samples[1],  # sup strong
              unlabel_samples[0],  # unsup weak
              unlabel_samples[1],  # unsup strong
          )
  
imports: import copy
  import os
  import traceback
  import six
  import sys
  import numpy
  import paddle
  import paddle.nn.functional
  from copy import deepcopy
  from paddle.io import DataLoader, DistributedBatchSampler
  from .utils import default_collate_fn
  from ppdet.core.workspace import register
  from .None import transform
  from .shm_utils import _get_shared_memory_size_in_M
  from ppdet.utils.logger import setup_logger
label_desc: Use image node_id 2 for calling the CombineSSODLoader obj's underlying member method code with example usage: obj.__iter__() without return types