      def default_response_headers(self):
          headers = {
              'Allow': ', '.join(self.allowed_methods),
          }
  
      def http_method_not_allowed(self, request, *args, **kwargs):
          """
          If `request.method` does not correspond to a handler method,
 
</s> remove         # TODO: Only vary by accept if multiple renderers
        return {
 </s> add         headers = { </s> remove             'Vary': 'Accept'
 </s> add 
        if len(self.renderer_classes) > 1:
            headers['Vary'] = 'Accept'
        return headers

      def default_response_headers(self):
          headers = {
              'Allow': ', '.join(self.allowed_methods),
          }
        if len(self.renderer_classes) > 1:
            headers['Vary'] = 'Accept'
        return headers

  
      def http_method_not_allowed(self, request, *args, **kwargs):
          """
          If `request.method` does not correspond to a handler method,
keep keep keep add keep keep keep keep
 Only add 'Vary: Accept' header when there is more than one possible renderer. 
rest_framework/views.py