code: def next(self):
          
          if self.iter_next():
              return DataBatch(data=self.getdata(), label=self.getlabel(), \
                      pad=self.getpad(), index=self.getindex())
          else:
              raise StopIteration
docs: Get next data batch from iterator.
  
          Returns
          -------
          DataBatch
              The data of next batch.
  
          Raises
          ------
          StopIteration
              If the end of the data is reached.