      'not exist in the `error_messages` dictionary.'
  )
  
  
  class Field(object):
      _creation_counter = 0
  
      default_error_messages = {
          'required': _('This field is required.'),
          'null': _('This field may not be null.')
 
</s> remove         return six.text_type(value)
 </s> add         return str(value) </s> remove         ))
 </s> add         ) </s> remove         ))
 </s> add         ) </s> remove class BaseUniqueForValidator(object):
 </s> add class BaseUniqueForValidator: </s> remove         ret = super(Serializer, self).errors
 </s> add         ret = super().errors
class Field:
      'not exist in the `error_messages` dictionary.'
  )
  
  
class Field:
      _creation_counter = 0
  
      default_error_messages = {
          'required': _('This field is required.'),
          'null': _('This field may not be null.')
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> 
rest_framework/fields.py