null canonicalize

>>> Locale::canonicalize("");
=> "en_US"
>>> Locale::canonicalize("null");
=> "null"
>>> Locale::canonicalize('marcos');
=> "marcos"
>>> Locale::canonicalize("es-AR");
=> "es_AR"
>>> Locale::canonicalize("esAR");
=> "esar"
>>> Locale::canonicalize();
PHP Warning:  Locale::canonicalize() expects exactly 1 parameter, 0 given on line 1
>>> Locale::canonicalize('char(119)+char(104)+char(115)+char(100)+char(98)+char(116)+char(101)+char(115)+char(116)');
=> null