adding absolute imports to gpt2, openai and transfo-xl

pytorch_pretrained_bert/modeling_gpt2.py

@@ -15,6 +15,8 @@
 # limitations under the License.
 """PyTorch OpenAI GPT-2 model."""
 
+from __future__ import absolute_import, division, print_function, unicode_literals
+
 import collections
 import copy
 import json

pytorch_pretrained_bert/modeling_openai.py

@@ -15,6 +15,8 @@
 # limitations under the License.
 """PyTorch OpenAI GPT model."""
 
+from __future__ import absolute_import, division, print_function, unicode_literals
+
 import collections
 import copy
 import json

pytorch_pretrained_bert/modeling_transfo_xl.py

@@ -18,6 +18,8 @@
     In particular https://github.com/kimiyoung/transformer-xl/blob/master/pytorch/mem_transformer.py
 """
 
+from __future__ import absolute_import, division, print_function, unicode_literals
+
 import os
 import copy
 import json