/**
* Fix the registration number
*
* Transform out leading 0s and non numeric chars before processing input
* This way if we remove everything there will still be ab error for required input being blank
* @param array $arr
* @return \Foundation\Form\Input or boolean
*/
public function validateInput($arr)
{
$element = $this->_applicationPage->getPage()->getElementByFixedId(self::FID_REGISTRATION_NUMBER);
$key = 'el' . $element->getId();
$arr[$key] = preg_replace('#[^0-9]#', '', $arr[$key]);
$arr[$key] = ltrim($arr[$key], '0');
return parent::validateInput($arr);
}