Missing request_token

<pre class="CodeBlock"><code><?php
        include 'kiteconnect.php';

        //Hard coded values
        $api_key = "******";
        $secret_key = "*******";

        // Incoming from the redirect.
        $request_token = $_GET["request_token"];
        echo "
        Request Token is: ".$request_token;

        $checksum = hash("sha256", $api_key . $request_token . $secret_key);
        echo "
        CheckSum is: ".$checksum;

        $kite = new KiteConnect($api_key);
        try {
        $user = $kite->requestAccessToken($request_token, $secret_key);
        echo "Authentication successful. \n";
        print_r($user);
        $kite->setAccessToken($user->access_token);
        } catch(Exception $e) {
        echo "Authentication failed: ".$e->getMessage();
        throw $e;
        }
        echo $user->user_id." has logged in";
        
	?>