                      params={'key': key},
                  )
  
      def to_python(self, value):
          if isinstance(value, six.string_types):
              value = json.loads(value)
          return value
  
      def value_to_string(self, obj):
          return json.dumps(self.value_from_object(obj))
 
</s> remove         if isinstance(value, six.string_types):
 </s> add         if isinstance(value, str): </s> remove         if isinstance(value, six.string_types):
 </s> add         if isinstance(value, str): </s> remove         if isinstance(value, six.string_types) or value is None:
 </s> add         if isinstance(value, str) or value is None: </s> remove             return self.delimiter.join(six.text_type(self.base_field.prepare_value(v)) for v in value)
 </s> add             return self.delimiter.join(str(self.base_field.prepare_value(v)) for v in value) </s> remove         return six.text_type(value.title)
 </s> add         return str(value.title)
        if isinstance(value, str):
                      params={'key': key},
                  )
  
      def to_python(self, value):
        if isinstance(value, str):
              value = json.loads(value)
          return value
  
      def value_to_string(self, obj):
          return json.dumps(self.value_from_object(obj))
keep keep keep keep replace keep keep keep keep keep
 Refs #23919 -- Removed six.<various>_types usage

Thanks Tim Graham and Simon Charette for the reviews. 
django/contrib/postgres/fields/hstore.py