I can’t fetch batch from dataloader now.
inputs, masks = next(iter(dataloaders['train']))

I am getting the following error:
NotImplementedError                       Traceback (most recent call last)
<ipython-input-19-fbb099c4b6b9> in <module>()
     13 # Get a batch of training data
     14 
---> 15 inputs, masks = next(iter(dataloaders['train']))
     16 
     17 print(inputs.shape, masks.shape)

/home/gul/anaconda2/lib/python2.7/site-packages/torch/utils/data/dataloader.pyc in __iter__(self)
    817 
    818     def __iter__(self):
--> 819         return _DataLoaderIter(self)
    820 
    821     def __len__(self):

/home/gul/anaconda2/lib/python2.7/site-packages/torch/utils/data/dataloader.pyc in __init__(self, loader)
    582             # prime the prefetch loop
    583             for _ in range(2 * self.num_workers):
--> 584                 self._put_indices()
    585 
    586     def __len__(self):

/home/gul/anaconda2/lib/python2.7/site-packages/torch/utils/data/dataloader.pyc in _put_indices(self)
    644     def _put_indices(self):
    645         assert self.batches_outstanding < 2 * self.num_workers
--> 646         indices = next(self.sample_iter, None)
    647         if indices is None:
    648             return

/home/gul/anaconda2/lib/python2.7/site-packages/torch/utils/data/sampler.pyc in __iter__(self)
    158     def __iter__(self):
    159         batch = []
--> 160         for idx in self.sampler:
    161             batch.append(idx)
    162             if len(batch) == self.batch_size:

/home/gul/anaconda2/lib/python2.7/site-packages/torch/utils/data/sampler.pyc in __iter__(self)
     32 
     33     def __iter__(self):
---> 34         return iter(range(len(self.data_source)))
     35 
     36     def __len__(self):

/home/gul/anaconda2/lib/python2.7/site-packages/torch/utils/data/dataset.pyc in __len__(self)
     18 
     19     def __len__(self):
---> 20         raise NotImplementedError
     21 
     22     def __add__(self, other):

NotImplementedError: