fvar(_old_)
  _old_ = block.select(BLK_FUNC)
  if(not block.empty())
    println('')
  end
  block.select(_old_)
  block.copyto(BLK_FUNC)
  block.delete(block.select(BLK_FUNC))
  block.copyto(func_old_blk_body)
  block.delete(block.select(func_old_blk_body))
  if(func_old_blk_func)
    BLK_FUNC = func_old_blk_func
  else 
    free(BLK_FUNC)
  end