def __call__(self, data):
sample_len = len(data) // self._batch_size<EOL>return SimpleDataset(<EOL>mx.nd.array(<EOL>self._vocab[data[:sample_len * self._batch_size]]).reshape(<EOL>self._batch_size, -<NUM_LIT:1>).T)<EOL>
Batchify a dataset.

        Parameters
        ----------
        data : mxnet.gluon.data.Dataset
            A flat dataset to be batchified.

        Returns
        -------
        mxnet.gluon.data.Dataset
            NDArray of shape (len(data) // N, N) where N is the batch_size
            wrapped by a mxnet.gluon.data.SimpleDataset. Excessive tokens that
            don't align along the batches are discarded.