public static function invalidKeys()
{
return [['{str', '_str'], ['rand{', 'rand_'], ['rand{str', 'rand_str'], ['rand}str', 'rand_str'], ['rand(str', 'rand_str'], ['rand)str', 'rand_str'], ['rand/str', 'rand_str'], ['rand\\str', 'rand_str'], ['rand@str', 'rand_str'], ['rand:str', 'rand_str']];
}