def similarity(self,rect):
        i = self.intersect(rect)
        if i == None:
            return 0.0
        return i.area() / (0.5*self.area() + 0.5*rect.area())
L{NewsBuilder._changeVersions} gets the release date for a given
dataset/ETHPy150Open bolme/pyvision/src/pyvision/types/Rect.py/Rect.similarity--crossover with--dataset/ETHPy150Open twisted/twisted/twisted/python/test/test_release.py/NewsBuilderMixin.test_changeVersionInNews