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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_body(self, body='', refresh_token=None, scope=None, **kwargs):
 """Prepare an access token request, using a refresh token. If the authorization server issued a refresh token to the client, the client makes a refresh request to the token endpoint by adding the following parameters using the "application/x-www-form-urlencoded" format in the HTTP request entity-body: grant_type REQUIRED. Value MUST be set to "refresh_token". refresh_token REQUIRED. The refresh token issued to the client. scope OPTIONAL. The scope of the access request as described by Section 3.3. The requested scope MUST NOT include any scope not originally granted by the resource owner, and if omitted is treated as equal to the scope originally granted by the resource owner. """

        refresh_token = refresh_token or self.refresh_token
        return prepare_token_request(self.refresh_token_key, body=body, scope=scope,
                                     refresh_token=refresh_token, **kwargs)