  from django.core.exceptions import PermissionDenied
  from django.core.mail import send_mail
  from django.db import models
  from django.db.models.manager import EmptyManager
  from django.utils import six, timezone
  from django.utils.translation import ugettext_lazy as _
  
  from .validators import UnicodeUsernameValidator
  
  
 
</s> remove from django.utils import six
 </s> add  </s> remove from django.utils import six, timezone
 </s> add from django.utils import timezone </s> remove from django.utils import six
 </s> add  </s> remove from django.utils import six
 </s> add  </s> remove from django.utils import six, timezone
 </s> add from django.utils import timezone
from django.utils import timezone
  from django.core.exceptions import PermissionDenied
  from django.core.mail import send_mail
  from django.db import models
  from django.db.models.manager import EmptyManager
from django.utils import timezone
  from django.utils.translation import ugettext_lazy as _
  
  from .validators import UnicodeUsernameValidator
  
  
keep keep keep keep replace keep keep keep keep keep
 Refs #23919 -- Removed six.<various>_types usage

Thanks Tim Graham and Simon Charette for the reviews. 
django/contrib/auth/models.py