public void PackTo(ref TupleWriter writer)
 {
     if (m_packed.IsPresent)
     {
         writer.Output.WriteBytes(in m_packed);
     }
 }
 void ITupleSerializable.PackTo(ref TupleWriter writer)
 {
     TuplePackers.SerializeTo <T1>(ref writer, this.Item1);
 }