public function GetValidVouchers( $customer_id, $event_id, $contact_person_id = null ) {
		$params = array();
		if ( isset( $contact_person_id ) ) {
			$params['contactPersonId'] = $contact_person_id;
		}

		return parent::GET(
			"/$customer_id/ValidVouchers/$event_id",
			$params,
			get_called_class() . '|' . __FUNCTION__
		);
	}
public function GetValidVouchers( $customer_id, $event_id, $contact_person_id = null ) {
		$params = array();
		if ( isset( $contact_person_id ) ) {
			$params['contactPersonId'] = $contact_person_id;
		}

		return parent::GET(
			"/$customer_id/ValidVouchers/$event_id",
			$params,
			get_called_class() . '|' . __FUNCTION__
		);
	}
@param integer $customer_id
@param integer $event_id
@param integer|null $contact_person_id

@return mixed