code: void setBlock(final int index, final Block b) {
      blockList[index2BlockId(index)] = b.getBlockId();
      blockList[index2BlockLen(index)] = b.getNumBytes();
      blockList[index2BlockGenStamp(index)] = b.getGenerationStamp();
    }
docs: Set the indexTh block
  @param index - the index of the block to set
  @param b - the block is set to the value of the this block