docs: public static double getLPNormP(AbstractMTree<?, ?, ?, ?> tree) {
      // Note: we deliberately lose generics here, so the compilers complain
      // less on the next typecheck and cast!
      DistanceFunction<?> distanceFunction = tree.getDistanceFunction();
      if(LPNormDistanceFunction.class.isInstance(distanceFunction)) {
        return ((LPNormDistanceFunction) distanceFunction).getP();
      }
      return 0;
    }