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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 subparsers(self):
 """ Insantiates the subparsers for all commands """

        if self._subparsers is None:
            apkw = {
                'title': 'commands',
                'description': 'Commands for the %s program' % self.parser.prog,
            }
            self._subparsers = self.parser.add_subparsers(**apkw)
        return self._subparsers