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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 _realPath(self, newPathName: str = None) -> str: """ Private Real Path Get path name. @param newPathName: variable for new path name if passed argument. @type newPathName: String @return: Path Name as string. """


        directory = self._directory()
        assert directory
        return os.path.join(directory.path,
                            newPathName if newPathName else self._pathName)