def setdefault(self, key, defval=None):
        if key in self:
            return self[key]
        else:
            self[key] = defval
            return defval
>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
dataset/ETHPy150Open editorconfig/editorconfig-vim/plugin/editorconfig-core-py/editorconfig/odict.py/OrderedDict.setdefault