def getDrives(self):
        '''Assign all available cd drives to self.drives. If CdRom.drive
        is not already set the first drive returned becomes the default.
        '''
        letters = [l.upper() + ':' for l in 'abcdefghijklmnopqrstuvwxyz']
        for drive in letters:
            if win32file.GetDriveType(drive)==5:
                self.drives.append(drive)
        if not self.drive:
            self.drive = self.drives[0]
Assign all available cd drives to self.drives. If CdRom.drive
        is not already set the first drive returned becomes the default.
        
recipes/Python/180919_Windows_CDRom_Module/recipe-180919.py