Override the helper function for batchifying data

def _batchify(self, batch_data, batch_label, start=0):
        """Override the helper function for batchifying data"""
        i = start
        batch_size = self.batch_size
        try:
            while i < batch_size:
                label, s = self.next_sample()
                data = self.imdecode(s)
                try:
                    self.check_valid_image([data])
                    label = self._parse_label(label)
                    data, label = self.augmentation_transform(data, label)
                    self._check_valid_label(label)
                except RuntimeError as e:
                    logging.debug('Invalid image, skipping:  %s', str(e))
                    continue
                for datum in [data]:
                    assert i < batch_size, 'Batch size must be multiples of augmenter output length'
                    batch_data[i] = self.postprocess_data(datum)
                    num_object = label.shape[0]
                    batch_label[i][0:num_object] = nd.array(label)
                    if num_object < batch_label[i].shape[0]:
                        batch_label[i][num_object:] = -1
                    i += 1
        except StopIteration:
            if not i:
                raise StopIteration

        return i