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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 add_arguments(self, parser):
 """ Define optional arguments with default values """

        parser.add_argument('--length', default=self.length,
                            type=int, help=_('SECRET_KEY length default=%d' % self.length))

        parser.add_argument('--alphabet', default=self.allowed_chars,
                            type=str, help=_('alphabet to use default=%s' % self.allowed_chars))