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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 num(self, count=None, show=None):
 # (;$count,$show) """ Set the number to be used in other method calls. Returns count. Set show to False to return '' instead. """

        if count is not None:
            try:
                self.persistent_count = int(count)
            except ValueError:
                raise BadNumValueError
            if (show is None) or show:
                return str(count)
        else:
            self.persistent_count = None
        return ""