$myParam = CRM_Utils_Request::retrieve('myParam', 'String');
$myPostParam = CRM_Utils_Request::retrieve('myPostParam', 'String', $this, true);
$myDefaultParam = CRM_Utils_Request::retrieve('myDefaultParam', 'String', $this, false, 'default');This retrieves a parameter named 'myDefaultParam', and if it is not found, it assigns a default value of 'default'. Overall, CRM_Utils_Request is a very helpful class for handling and retrieving request parameters in PHP, and it is part of the CiviCRM package.