Check whether the range can still be used, or has been invalidated.
bool isValid() pure nothrow @property const;
ResultRange becomes invalidated (and thus cannot be used) when the server
is sent another command on the same connection. When an invalidated
is used, a
MYXInvalidatedRange is thrown. If you need to
send the server another command, but still access these results afterwords,
you can save the results for later by converting this range to an array via