  import traceback
  from collections import Mapping, OrderedDict
  
  from django.core.exceptions import ImproperlyConfigured
  from django.db import models
  from django.db.models import DurationField as ModelDurationField
  from django.db.models.fields import Field as DjangoModelField
  from django.db.models.fields import FieldDoesNotExist
  from django.utils import six, timezone
 
</s> remove from django.core.exceptions import ValidationError as DjangoValidationError
 </s> add  </s> remove from django.core.exceptions import ValidationError as DjangoValidationError
 </s> add  </s> remove from django.test.client import RequestFactory as DjangoRequestFactory
 </s> add  </s> remove from django.core.paginator import Paginator as DjangoPaginator
 </s> add 
from django.core.exceptions import ValidationError as DjangoValidationError
  import traceback
  from collections import Mapping, OrderedDict
  
  from django.core.exceptions import ImproperlyConfigured
from django.core.exceptions import ValidationError as DjangoValidationError
  from django.db import models
  from django.db.models import DurationField as ModelDurationField
  from django.db.models.fields import Field as DjangoModelField
  from django.db.models.fields import FieldDoesNotExist
  from django.utils import six, timezone
keep keep keep add keep keep keep keep keep
 Upgrade isort (#5817)

* Fix isort

* runtests: add --diff to ISORT_ARGS

* requirements-codestyle: bump isort to 4.3.3

* isort: move config to setup.cfg 
rest_framework/serializers.py