错误：调用未定义的方法GuzzleHttp \ Client :: request

如何解决错误：调用未定义的方法GuzzleHttp \ Client :: request

我尝试导入

use GuzzleHttp;
use GuzzleHttp\Subscriber\Oauth\Oauth1;

但是它不起作用，它总是给我同样的PHP错误致命错误：

未捕获的错误：调用未定义的方法GuzzleHttp \ Client :: request（）

在我调用请求方法的那一行

<?PHP
require_once 'config.PHP';

try {
    
   $client = new GuzzleHttp\Client(['base_uri' => 'https://zoom.us']);
 
    $response = $client->request('POST','/oauth/token',[
        "headers" => [
            "Authorization" => "Basic ". base64_encode(CLIENT_ID.':'.CLIENT_SECRET)
        ],'form_params' => [
            "grant_type" => "authorization_code","code" => $_GET['code'],"redirect_uri" => REDIRECT_URI
        ],]);
 
    $token = json_decode($response->getBody()->getContents(),true);
 
    $db = new DB();
 
    if($db->is_table_empty()) {
        $db->update_access_token(json_encode($token));
        echo "Access token inserted successfully.";
    }
} catch(Exception $e) {
    echo $e->getMessage();
}
?>