[WordSeg] Add validation (#538)
[WordSeg] Add validation (#538)

* Add validation

* Add bpc

* Remove regularization from validation loss

* Guard against no validation data

Co-authored-by: Brennan Saeta <1a2d80f746a3f5be27b2f3560ad0083b71c57f3a@gmail.com>

* Print training loss if no validation

Co-authored-by: Brennan Saeta <1a2d80f746a3f5be27b2f3560ad0083b71c57f3a@gmail.com>
tensorflow/swift-models,tensorflow/swift-models,tensorflow/swift-models,tensorflow/swift-models