build/transaction.go
func (m MemoReturn) MutateTransaction(o *TransactionBuilder) (err error) {
	o.TX.Memo, err = xdr.NewMemo(xdr.MemoTypeMemoReturn, m.Value)
	return
}
func (m MemoReturn) MutateTransaction(o *TransactionBuilder) (err error) {
	o.TX.Memo, err = xdr.NewMemo(xdr.MemoTypeMemoReturn, m.Value)
	return
}
// MutateTransaction for MemoReturn sets the memo.