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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def prepare_refresh_token_request(self, token_url, refresh_token=None, body='', scope=None, **kwargs):
 """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). """

        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