Test\Helper::decodedClientToken PHP Method

    public static function decodedClientToken($params = [])
    {
        $encodedClientToken = Braintree\ClientToken::generate($params);
        return base64_decode($encodedClientToken);
    }

 public function nonceForPayPalAccount($options)
 {
     $clientToken = json_decode(Test\Helper::decodedClientToken());
     $options["authorization_fingerprint"] = $clientToken->authorizationFingerprint;
     $response = $this->post('/client_api/v1/payment_methods/paypal_accounts.json', json_encode($options));
     if ($response["status"] == 201 || $response["status"] == 202) {
         $body = json_decode($response["body"], true);
         return $body["paypalAccounts"][0]["nonce"];
     } else {
         throw new Exception(var_dump($response));
     }
 }