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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 exception_message(self) -> Union[str, None]: """ On Lavalink V3, if there was an exception during a load or get tracks call this property will be populated with the error message. If there was no error this property will be ``None``. """

        if self.has_error:
            exception_data = self._raw.get("exception", {})
            return exception_data.get("message")
        return None