Merge pull request #1 from tensorflow/master

new pull

official/nlp/modeling/networks/__init__.py

-# Copyright 2019 The TensorFlow Authors. All Rights Reserved.
+# Copyright 2021 The TensorFlow Authors. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -11,11 +11,21 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-# ==============================================================================
-"""Networks package definition."""
-from official.nlp.modeling.networks.albert_transformer_encoder import AlbertTransformerEncoder
+
+"""Networks are combinations of `tf.keras` layers (and possibly other networks).
+
+They are `tf.keras` models that would not be trained alone. It encapsulates
+common network structures like a transformer encoder into an easily
+handled object with a standardized configuration.
+"""
+from official.nlp.modeling.networks.albert_encoder import AlbertEncoder
+from official.nlp.modeling.networks.bert_encoder import BertEncoder
 from official.nlp.modeling.networks.classification import Classification
 from official.nlp.modeling.networks.encoder_scaffold import EncoderScaffold
+from official.nlp.modeling.networks.mobile_bert_encoder import MobileBERTEncoder
+from official.nlp.modeling.networks.packed_sequence_embedding import PackedSequenceEmbedding
 from official.nlp.modeling.networks.span_labeling import SpanLabeling
-from official.nlp.modeling.networks.token_classification import TokenClassification
-from official.nlp.modeling.networks.transformer_encoder import TransformerEncoder
+from official.nlp.modeling.networks.span_labeling import XLNetSpanLabeling
+from official.nlp.modeling.networks.xlnet_base import XLNetBase
+# Backward compatibility. The modules are deprecated.
+TransformerEncoder = BertEncoder