  
  from django.conf import settings
  from django.core.exceptions import ValidationError as DjangoValidationError
  from django.core.exceptions import ObjectDoesNotExist
  from django.core.validators import RegexValidator, ip_address_validators
  from django.forms import FilePathField as DjangoFilePathField
  from django.forms import ImageField as DjangoImageField
  from django.utils import six, timezone
 
</s> remove USER_SETTINGS = getattr(settings, 'REST_FRAMEWORK', None)
 </s> add  </s> remove         self.user_settings = user_settings or {}
 </s> add         if user_settings:
            self._user_settings = user_settings </s> remove         if self.format is None:
 </s> add         if output_format is None: </s> remove         if self.format is None:
 </s> add         output_format = getattr(self, 'format', api_settings.TIME_FORMAT)

        if output_format is None: </s> remove         if self.format.lower() == ISO_8601:
 </s> add         if output_format.lower() == ISO_8601:
from django.core.exceptions import ImproperlyConfigured
  
  from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
  from django.core.exceptions import ValidationError as DjangoValidationError
  from django.core.exceptions import ObjectDoesNotExist
  from django.core.validators import RegexValidator, ip_address_validators
  from django.forms import FilePathField as DjangoFilePathField
  from django.forms import ImageField as DjangoImageField
  from django.utils import six, timezone
keep add keep keep keep keep keep keep
 Access settings lazily, not at module import 
rest_framework/fields.py