def compute_percentile(self, percentage):
        """
        Returns a Position object that represents percentage%-far-of-the-way
        through the larger task, as specified by this query.

        @param percentage    a number between 0 and 100.
        """
        all_patches = self.get_all_patches()
        return all_patches[
            int(len(all_patches) * percentage / 100)
        ].start_position
Returns a Position object that represents percentage%-far-of-the-way
        through the larger task, as specified by this query.

        @param percentage    a number between 0 and 100.