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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 _settings_part(self):
 """ A |SettingsPart| object providing access to the document-level settings for this document. Creates a default settings part if one is not present. """

        try:
            return self.part_related_by(RT.SETTINGS)
        except KeyError:
            settings_part = SettingsPart.default(self.package)
            self.relate_to(settings_part, RT.SETTINGS)
            return settings_part