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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_root(self, drive):
 """ Returns the root directory for the specified drive, creating it if necessary. """

        drive = _my_normcase(drive)
        try:
            return self.Root[drive]
        except KeyError:
            root = RootDir(drive, self)
            self.Root[drive] = root
            if not drive:
                self.Root[self.defaultDrive] = root
            elif drive == self.defaultDrive:
                self.Root[''] = root
            return root