public static function validateMultiple($keys)
    {
        foreach ($keys as $key) {
            if (!is_string($key) && !is_int($key)) {
                throw InvalidKeyException::forKey($key);
            }
        }
    }
public static function validateMultiple($keys)
    {
        foreach ($keys as $key) {
            if (!is_string($key) && !is_int($key)) {
                throw InvalidKeyException::forKey($key);
            }
        }
    }
public static function validateMultiple ( $ keys ) { foreach ( $ keys as $ key ) { if ( ! is_string ( $ key ) && ! is_int ( $ key ) ) { throw InvalidKeyException :: forKey ( $ key ) ; } } }
Validates that multiple keys are valid.

@param array $keys The tested keys.

@throws InvalidKeyException If a key is invalid.
Validates that multiple keys are valid .