Integer Tensor; the sequence of token ids in this example.
input_mask
Integer Tensor; sequence of 1s (for "real" tokens) and 0s
(for padding tokens).
segment_ids
Integer Tensor; aka token_type_ids. Indicators for which
sentence (or sequence each token belongs to). Classical BERT supports only
0s and 1s (for first and second sentence, respectively).
label_id
Integer; represents training example classification labels.
is_real_example
Logical; later on this is used as a flag for whether
to "count" this example for calculating accuracy and loss.