Warning: Undefined variable $soap in C:\Wamp64\www\xades\send_soap_guzzle.php on line 8

Fatal error: Uncaught Error: Class "GuzzleHttp\Client" not found in C:\Wamp64\www\xades\send_soap_guzzle.php:18 Stack trace: #0 {main} thrown in C:\Wamp64\www\xades\send_soap_guzzle.php on line 18