code: public Promise<Void> truncate(long size) {
  		return sanitize(ofBlockingRunnable(executor, () -> {
  			try {
  				channel.truncate(size);
  			} catch (IOException e) {
  				throw new UncheckedException(e);
  			}
  		}));
  	}
docs: Truncates this file to the given size. If current size
  of the file is greater than {@code size}, all bytes
  beyond the new size will be discarded.
  
  @param size the new size, a non-negative byte count