def shouldStillKeepGoing(self, path):
        dist = sum(vector.distance for vector in path.of(IDistance))
        ok = (self.distance >= dist)
        return ok
Implement L{IRetriever.shouldKeepGoing} to stop for paths whose sum of
dataset/ETHPy150Open twisted/imaginary/imaginary/idea.py/Proximity.shouldStillKeepGoing