def popitem(self):
        '''D.popitem() -> (k, v). Remove and return a (key, value) pair with
        the largest key; raise KeyError if D is empty.'''
        try:
            key = self._sorted_keys.pop()
        except IndexError:
            raise KeyError('popitem(): dictionary is empty')
        else:
            return key, dict.pop(self, key)
D.popitem() -> (k, v). Remove and return a (key, value) pair with
        the largest key; raise KeyError if D is empty.
recipes/Python/576998_Sorted_dictionary/recipe-576998.py