def _get_prop_name(self):
    raise NotImplementedError
Algorithm: pivoting. Similar concept as QuickSort
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/datastore/datastore_query.py/_SinglePropertyFilter._get_prop_name--crossover with--dataset/ETHPy150Open algorhythms/LeetCode/075 Sort Colors.py/Solution.sortColors