src/Utility/Hash.php
protected static function matchToken($key, $token)
    {
        if ($token === '{n}') {
            return is_numeric($key);
        }
        if ($token === '{s}') {
            return is_string($key);
        }
        if (is_numeric($token)) {
            return ($key == $token);
        }

        return ($key === $token);
    }
protected static function matchToken($key, $token)
    {
        if ($token === '{n}') {
            return is_numeric($key);
        }
        if ($token === '{s}') {
            return is_string($key);
        }
        if (is_numeric($token)) {
            return ($key == $token);
        }

        return ($key === $token);
    }
Check a key against a token.

@param string $key The key in the array being searched.
@param string $token The token being matched.

@return bool