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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 save(self, filename):
 """Saves the TranslationUnit to a file. This is equivalent to passing -emit-ast to the clang frontend. The saved file can be loaded back into a TranslationUnit. Or, if it corresponds to a header, it can be used as a pre-compiled header file. If an error occurs while saving, a TranslationUnitSaveError is raised. If the error was TranslationUnitSaveError.ERROR_INVALID_TU, this means the constructed TranslationUnit was not valid at time of save. In this case, the reason(s) why should be available via TranslationUnit.diagnostics(). filename -- The path to save the translation unit to. """

        options = conf.lib.clang_defaultSaveOptions(self)
        result = int(conf.lib.clang_saveTranslationUnit(self, filename,
                                                        options))
        if result != 0:
            raise TranslationUnitSaveError(result,
                'Error saving TranslationUnit.')