public final void clean() {
        // If this space has no entities, the left and right spaces will
        // be empty, too. Preemptive halt.
        if(entities.isEmpty()) {
            return;
        }

        types.clear();
        entities.clear();

         // If there are no left and right spaces, halt.
        if(!isLeaf() && hasDisbursed) {
            // Recurse into the deep:
            for(Space space : nodes) {
                space.clean();
            }
        }

        hasDisbursed = false;
    }