@property
    def row_names(self):
        return self._row_names
Given entity primary key as Reference Proto, returns entity group.
dataset/ETHPy150Open wireservice/agate/agate/table/__init__.py/Table.row_names--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/analytics/entity.py/EntityGroupName