Clawback)   if err != nil {    reportErrorf("Cannot construct transaction: %s", err)   }    tx.Note = parseNoteField(cmd)   tx.Lease = parseLease(cmd)    firstValid, lastValid, err = client.ComputeValidityRounds(firstValid, lastValid, numValidRounds)   if err != nil {    reportErrorf("Cannot determine last valid round: %s", err)   }   tx, err = client.FillUnsignedTxTemplate(