function authorise($clientId, $clientSecret
    $b64 = base64_encode($clientId.":".$clientSecret
    $cURLConnection = curl_init(
    $url = "https://api.sandbox.ebay.com/identity/v1/oauth2/token";

    $postFields = array(
        'grant_type' => 'client_credentials',
        'scope' => 'https://api.ebay.com/oauth/api_scope'
    );

    curl_setopt($cURLConnection, CURLOPT_URL, $url);
    curl_setopt($cURLConnection, CURLOPT_POST, true);
    curl_setopt($cURLConnection, CURLOPT_HTTPHEADER, array(
        "Authorization:Basic $b64",
        "Content-Type:application/x-www-form-urlencoded"
    ));

    curl_setopt($cURLConnection, CURLOPT_POSTFIELDS, json_encode($postFields))
    $response = curl_exec($cURLConnection);
    curl_close($cURLConnection);

    $result = json_decode($response, true);