code: func (r *Receipt) Size() common.StorageSize {
  	size := common.StorageSize(unsafe.Sizeof(*r)) + common.StorageSize(len(r.PostState))
  
  	size += common.StorageSize(len(r.Logs)) * common.StorageSize(unsafe.Sizeof(Log{}))
  	for _, log := range r.Logs {
  		size += common.StorageSize(len(log.Topics)*common.HashLength + len(log.Data))
  	}
  	return size
  }
docs: // Size returns the approximate memory used by all internal contents. It is used
  // to approximate and limit the memory consumption of various caches.