Get the index of the bucket that the given node would fall into.

def get_bucket_for(self, node):
        """
        Get the index of the bucket that the given node would fall into.
        """
        for index, bucket in enumerate(self.buckets):
            if node.long_id < bucket.range[1]:
                return index
        # we should never be here, but make linter happy
        return None