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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 to_yaml(self, ignore_none: bool=True, ignore_empty: bool=False) -> str: """From instance to yaml string :param ignore_none: Properties which is None are excluded if True :param ignore_empty: Properties which is empty are excluded if True :return: Yaml string Usage: favorites: - name: Apple names_by_lang: de: Apfel en: Apple - name: Orange id: 1 name: Tom <BLANKLINE> """

        return util.dump_yaml(traverse(self, ignore_none, force_value=True, ignore_empty=ignore_empty))