code: void copyBlocksTo(RegularFile target, int count) {
      int start = blockCount - count;
      int targetEnd = target.blockCount + count;
      target.expandIfNecessary(targetEnd);
  
      System.arraycopy(this.blocks, start, target.blocks, target.blockCount, count);
      target.blockCount = targetEnd;
    }
docs: Copies the last {@code count} blocks from this file to the end of the given target file.