code: public void updateToRemovedBlock(boolean add, long blockId) {
      if (add) {
        if (mBlocks.contains(blockId)) {
          mToRemoveBlocks.add(blockId);
        }
      } else {
        mToRemoveBlocks.remove(blockId);
      }
    }
docs: Adds or removes a block from the to-be-removed blocks set of the worker.
  
  @param add true if to add, to remove otherwise
  @param blockId the id of the block to be added or removed