'Add a MAC token to the request authorization header.'

def _add_mac_token(self, uri, http_method=u'GET', body=None, headers=None, token_placement=AUTH_HEADER):

    headers = prepare_mac_header(self.token, uri, self.key, http_method, headers=headers, body=body, ext=self.ext, hash_algorithm=self.hash_algorithm)
    return (uri, headers, body)
