title: Why am I getting this error: Class "Google_Service_Calendar" not found?
body: <p>Here is my code: this is just a sample Quickstart.php from Google Developers:</p>
  
  <pre><code>require __DIR__ . '/vendor/autoload.php';
  
  
  define('APPLICATION_NAME', 'Google Calendar API PHP Quickstart');
  define('CREDENTIALS_PATH', '~/.credentials/calendar-php-quickstart.json');
  define('CLIENT_SECRET_PATH', __DIR__ . '/client_secret.json');
  define('SCOPES', implode(' ', array(
      Google_Service_Calendar::CALENDAR_READONLY)));
  </code></pre>
  
  <p>the last line is throwing this error: "class Google_Service_Calendar" not found. Has anyone else experienced this?</p>