  response content is handled by parsers and renderers.
  """
  from __future__ import unicode_literals
  from django.db import models
  from django.db.models.fields import FieldDoesNotExist, Field as DjangoModelField
  from django.utils.functional import cached_property
  from django.utils.translation import ugettext_lazy as _
  from rest_framework.compat import (
      postgres_fields,
      unicode_to_repr,
 
</s> remove from rest_framework.compat import (
    postgres_fields,
    unicode_to_repr,
    DurationField as ModelDurationField,
 </s> add from django.db.models.fields import (
    FieldDoesNotExist, Field as DjangoModelField </s> remove from rest_framework.utils.field_mapping import (
    get_url_kwargs, get_field_kwargs,
    get_relation_kwargs, get_nested_relation_kwargs,
    ClassLookupDict
 </s> add from rest_framework.compat import (
    postgres_fields, unicode_to_repr, DurationField as ModelDurationField, </s> remove from django.core.exceptions import PermissionDenied
from django.http import Http404
 </s> add import inspect
import warnings

  response content is handled by parsers and renderers.
  """
  from __future__ import unicode_literals
  from django.db import models

  from django.utils.functional import cached_property
  from django.utils.translation import ugettext_lazy as _
  from rest_framework.compat import (
      postgres_fields,
      unicode_to_repr,
keep keep keep keep replace keep keep keep keep keep
 Cleanup import following PEP 8 style guide 
rest_framework/serializers.py