def iterate_graycode(self, k):
        unranked_code = GrayCode.unrank(self.superset_size,
                                       (self.rank_gray + k) % self.cardinality)
        return Subset.subset_from_bitlist(self.superset,
                                          unranked_code)
turn a mongodb-style record dict into a list.
dataset/ETHPy150Open sympy/sympy/sympy/combinatorics/subsets.py/Subset.iterate_graycode--crossover with--dataset/ETHPy150Open ipython/ipython-py3k/IPython/parallel/controller/sqlitedb.py/SQLiteDB._dict_to_list