use SelectSaver;
    {
       my $saver = new SelectSaver(FILEHANDLE);
       # FILEHANDLE is selected
    }
    # previous handle is selected
    {
       my $saver = new SelectSaver;
       # new handle may be selected, or not
    }
    # previous handle is selected
When a SelectSaver is destroyed, it re-selects the file handle that was selected when it was created.