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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _geograins(self):
 """Create a map geographic area terms to the geo grain GVid values """


        from geoid.civick import GVid

        geo_grains = {}

        for sl, cls in GVid.sl_map.items():
            if '_' not in cls.level:
                geo_grains[self.stem(cls.level)] = str(cls.nullval().summarize())

        return geo_grains