  from __future__ import unicode_literals
  
  import datetime
  import decimal
  from collections import OrderedDict
  
  import pytest
  from django.core.exceptions import ImproperlyConfigured
 
</s> remove        {py34,py35,py36}-django20,
       {py35,py36}-django21
       {py35,py36}-djangomaster,
 </s> add        {py34,py35,py36,py37}-django20,
       {py35,py36,py37}-django21
       {py35,py36,py37}-djangomaster, </s> remove       - env: DJANGO=2.1
 </s> add 
import sys
  from __future__ import unicode_literals
  
  import datetime
  import decimal
import sys
  from collections import OrderedDict
  
  import pytest
  from django.core.exceptions import ImproperlyConfigured
keep keep keep add keep keep keep keep
 Add Python 3.7 support (#6141) 
tests/test_model_serializer.py