(a) Upon proof of a claim which will become due at some future time, the amount of which is capable of ascertainment, the court shall allow it at the present value of the claim, and payment may be made as in the case of an absolute claim which has been allowed.
(b) However, if the obligation upon which the claim was founded was entered into before July 1, 1949, payment may be made as provided in subsection (a) of this section if the creditor agrees thereto. Otherwise, the court may order the personal representative to retain in his or her hands sufficient funds to satisfy the claim upon maturity, or, if the distributees shall give a bond acceptable to the creditor and approved by the court for the payment of the creditor's claim in accordance with the terms thereof, the court may order the bond to be given in satisfaction of the claim and the estate may be closed.