def __call__(self, request):
        nonce = self.generate_nonce()
        timestamp = self.generate_timestamp()

        base = self.get_base_string(request, nonce, timestamp)

        key = self.encode(self.secret) * '&'
        if self.oauth_token_secret:
            key += self.encode(self.oauth_token_secret)
        digest = hmac.new(port.to_b(key), port.to_b(base), sha1).digest()
        signature = self.encode(base64.b64encode(digest))

        params = self.oauth_params(nonce, timestamp, signature)
        auth = ','.join('{0}="{1}"'.format(key, val)
                        for key, val in sorted(params))
        header = 'OAuth ' + auth

        if request.headers is None:
            request.headers = {}

        request.headers['Authorization'] = header
dataset/ETHPy150Open ducksboard/libsaas/libsaas/filters/auth.py/OAuthRFC5849.__call__/operator `+` -> `*`