Fatal error: Uncaught Error: Call to a member function update() on string in /mnt/VenusReview/review/lyrasoft/dva/master/vendor/paypal/rest-api-sdk-php/sample/billing/UpdateBillingAgreement.php:36 Stack trace: #0 {main} thrown in /mnt/VenusReview/review/lyrasoft/dva/master/vendor/paypal/rest-api-sdk-php/sample/billing/UpdateBillingAgreement.php on line 36