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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 with_code(self, code):
 """ Sets a unique error code. This method returns reference to this exception to implement Builder pattern to chain additional calls. :param code: a unique error code :return: this exception object """

        self.code = code if code != None else 'UNKNOWN'
        self.name = code
        return self