549. Joint and separate debts.

549.     Joint and separate debts.

In the absence of agreement, express or implied1, there is no set-off between joint and separate debts2; but, if one joint debtor is a surety for the other, the principal debtor may set off against the joint debt a debt due to himself3; and a person induced to become surety by the creditor's fraud may set off his claim in respect of the fraud against the debt due by the principal debtor4.