code: func (z *Message) Msgsize() (s int) {
  	s = 1 + msgp.StringPrefixSize + len(z.Tag) + msgp.Int64Size + msgp.GuessSize(z.Record) + msgp.MapHeaderSize
  	if z.Option != nil {
  		for za0001, za0002 := range z.Option {
  			_ = za0002
  			s += msgp.StringPrefixSize + len(za0001) + msgp.StringPrefixSize + len(za0002)
  		}
  	}
  	return
  }
docs: // Msgsize returns an upper bound estimate of the number of bytes occupied by the serialized message