      }
      outputs = {
          datetime.date(2001, 1, 1): '2001-01-01',
          '2001-01-01': '2001-01-01',
          six.text_type('2016-01-10'): '2016-01-10',
          None: None,
          '': None,
      }
      field = serializers.DateField()
  
 
</s> remove         six.text_type('2016-01-10T00:00:00'): '2016-01-10T00:00:00',
 </s> add         str('2016-01-10T00:00:00'): '2016-01-10T00:00:00', </s> remove       - { python: "2.7", env: TOXENV=lint }
      - { python: "2.7", env: TOXENV=docs }
 </s> add       - { python: "3.7", env: TOXENV=lint }
      - { python: "3.7", env: TOXENV=docs } </s> remove       - { python: "2.7", env: DJANGO=1.11 }
 </s> add  </s> remove @six.add_metaclass(SerializerMetaclass)
class Serializer(BaseSerializer):
 </s> add class Serializer(BaseSerializer, metaclass=SerializerMetaclass): </s> remove         assert isinstance(self.pagination.to_html(), six.text_type)
 </s> add         assert isinstance(self.pagination.to_html(), str)
        str('2016-01-10'): '2016-01-10',
      }
      outputs = {
          datetime.date(2001, 1, 1): '2001-01-01',
          '2001-01-01': '2001-01-01',
        str('2016-01-10'): '2016-01-10',
          None: None,
          '': None,
      }
      field = serializers.DateField()
  
keep keep keep keep replace keep keep keep keep keep
 Dropped Python 2 compatibility. (#6615)

Thanks to Jon Dufresne (@jdufresne) for review.

Co-authored-by: Asif Saif Uddin <auvipy@gmail.com>
Co-authored-by: Rizwan Mansuri <Rizwan@webbyfox.com> 
tests/test_fields.py