code: func (z *IterGen) Msgsize() (s int) {
  	s = 1 + 3 + msgp.Uint32Size + 13 + msgp.Uint32Size + 2 + msgp.BytesPrefixSize + len(z.B)
  	return
  }
docs: // Msgsize returns an upper bound estimate of the number of bytes occupied by the serialized message