build/transaction.go
func (m MemoText) MutateTransaction(o *TransactionBuilder) (err error) {

	if len([]byte(m.Value)) > MemoTextMaxLength {
		err = errors.New("Memo too long; over 28 bytes")
		return
	}

	o.TX.Memo, err = xdr.NewMemo(xdr.MemoTypeMemoText, m.Value)
	return
}
func (m MemoText) MutateTransaction(o *TransactionBuilder) (err error) {

	if len([]byte(m.Value)) > MemoTextMaxLength {
		err = errors.New("Memo too long; over 28 bytes")
		return
	}

	o.TX.Memo, err = xdr.NewMemo(xdr.MemoTypeMemoText, m.Value)
	return
}
// MutateTransaction for MemoText sets the memo.