code: def prepare_refresh_token_request(self, token_url, refresh_token=None,
                                        body='', scope=None, **kwargs):
          
          if not is_secure_transport(token_url):
              raise InsecureTransportError()
  
          self.scope = scope or self.scope
          body = self.prepare_refresh_body(body=body,
                                           refresh_token=refresh_token, scope=self.scope, **kwargs)
          return token_url, FORM_ENC_HEADERS, body
docs: Prepare an access token refresh request.
  
          Expired access tokens can be replaced by new access tokens without
          going through the OAuth dance if the client obtained a refresh token.
          This refresh token and authentication credentials can be used to
          obtain a new access token, and possibly a new refresh token.
  
          :param token_url: Provider token refresh endpoint URL.
  
          :param refresh_token: Refresh token string.
  
          :param body: Existing request body (URL encoded string) to embed parameters
                       into. This may contain extra paramters. Default ''.
  
          :param scope: List of scopes to request. Must be equal to
          or a subset of the scopes granted when obtaining the refresh
          token.
  
          :param kwargs: Additional parameters to included in the request.
  
          :returns: The prepared request tuple with (url, headers, body).