add wireframe for seq2seq model

transformers/modeling_seq2seq.py

+# coding=utf-8
+# Copyright 2018 The HuggingFace Inc. team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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.
+""" Conditional generation class. """
+
+
+class Seq2SeqModel(object):
+    def __init__(self):
+        # need to use from_pretrained to initialize
+        raise NotImplementedError
+
+    @classmethod
+    def from_pretrained(cls, encoder, decoder):
+        # Here we should call AutoModel to initialize the models depending
+        # on the pretrained models taken as an input.
+        # For a first iteration we only work with Bert.
+        raise NotImplementedError
+
+    def __call__(self):
+        # allows to call an instance of the class
+        # model = Seq2Seq(encode='bert', decoder='bert')
+        raise NotImplementedError
+
+    def process(self):
+        # alternative API to __call__ it is more explicit.
+        raise NotImplementedError

transformers/tests/modeling_seq2seq_test.py

+# coding=utf-8
+# Copyright 2018 The Google AI Language Team Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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.
+import unittest
+
+
+class Seq2SeqTest(unittest.TestCase):
+    raise NotImplementedError
+
+
+def __main__():
+    unittest.main()