  from pytz.exceptions import InvalidTimeError
  
  from rest_framework import ISO_8601
  from rest_framework.compat import (
      Mapping, MaxLengthValidator, MaxValueValidator, MinLengthValidator,
      MinValueValidator, ProhibitNullCharactersValidator
  )
  from rest_framework.exceptions import ErrorDetail, ValidationError
  from rest_framework.settings import api_settings
  from rest_framework.utils import html, humanize_datetime, json, representation
 
</s> remove from rest_framework.compat import Mapping, postgres_fields
 </s> add from rest_framework.compat import postgres_fields </s> remove from rest_framework.compat import Mapping
 </s> add  </s> remove from rest_framework.compat import MutableMapping, coreapi
 </s> add from rest_framework.compat import coreapi
    MaxLengthValidator, MaxValueValidator, MinLengthValidator,
  from pytz.exceptions import InvalidTimeError
  
  from rest_framework import ISO_8601
  from rest_framework.compat import (
    MaxLengthValidator, MaxValueValidator, MinLengthValidator,
      MinValueValidator, ProhibitNullCharactersValidator
  )
  from rest_framework.exceptions import ErrorDetail, ValidationError
  from rest_framework.settings import api_settings
  from rest_framework.utils import html, humanize_datetime, json, representation
keep keep keep keep replace keep keep keep keep keep
 Remove unnecessary compatibility shims from rest_framework/compat.py (#6631)

For Python 3, collections.abc.Mapping and collections.abc.MutableMapping
are always available from the stdlib. 
rest_framework/fields.py