  from django import forms
  from django.conf import settings
  from django.core import validators
  from django.core.exceptions import ValidationError
  from django.utils import timezone
  from django.utils.datastructures import SortedDict
  from django.utils.dateparse import parse_date, parse_datetime, parse_time
  from django.utils.encoding import is_protected_type
  from django.utils.translation import ugettext_lazy as _
  from rest_framework import ISO_8601
 
</s> remove import django
import inspect
 </s> add  </s> remove from django.utils import timezone
 </s> add 
from django.utils import six, timezone
  from django import forms
  from django.conf import settings
  from django.core import validators
  from django.core.exceptions import ValidationError
from django.utils import six, timezone
  from django.utils.datastructures import SortedDict
  from django.utils.dateparse import parse_date, parse_datetime, parse_time
  from django.utils.encoding import is_protected_type
  from django.utils.translation import ugettext_lazy as _
  from rest_framework import ISO_8601
keep keep keep keep replace keep keep keep keep keep
 Use six.text_type instead of str everywhere 
rest_framework/fields.py