def setdefault(self, key, default=None):
        'od.setdefault(k[,d]) -> od.get(k,d), also set od[k]=d if k not in od'
        if key in self:
            return self[key]
        self[key] = default
        return default
od.setdefault(k[,d]) -> od.get(k,d), also set od[k]=d if k not in od
recipes/Python/576693_Ordered_Dictionary_for_Py24/recipe-576693.py