def ZoomForPixelSize(self, pixelSize ):
		
		for i in range(30):
			if pixelSize > self.Resolution(i):
				return i-1 if i!=0 else 0 # We don't want to scale up
Initializes a class that belongs to a polymorphic hierarchy.
dataset/ETHPy150Open Ecotrust/create-utfgrids/globalmaptiles.py/GlobalMercator.ZoomForPixelSize--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/db/polymodel.py/PolymorphicClass.__init__