code: func (b *Block) Size() common.StorageSize {
  	if size := b.size.Load(); size != nil {
  		return size.(common.StorageSize)
  	}
  	c := writeCounter(0)
  	rlp.Encode(&c, b)
  	b.size.Store(common.StorageSize(c))
  	return common.StorageSize(c)
  }
docs: // Size returns the true RLP encoded storage size of the block, either by encoding
  // and returning it, or returning a previsouly cached value.