docs: protected void writeForward(Encoder encoder) throws IOException {
      if (encoder.node.index != encoder.fromNode.index) {
        Bits bits = encoder.fromNode.bitsTo(encoder.node);
        short count = (short) (encoder.node.getDepth() - encoder.fromNode.getDepth());
        if (verbose != null) {
          verbose.println(String.format("Writing %s forward from %s to %s = %s", count, encoder.fromNode.getDebugString(), encoder.node.getDebugString(), bits));
        }
        encoder.out.writeVarShort(count, 3);
        encoder.out.write(bits);
      }
      else {
        assert (0 == encoder.node.index);
        encoder.out.writeVarShort((short) 0, 3);
      }
    }