21.—In the case of a sentence of death passed by a court-martial—
(a) the sentence shall not in any case be executed until after the expiration of the time within which notice of appeal to the Court may be given in accordance with rules of court, and
(b) if such notice is so given, the appeal shall be heard and determined with as much expedition as practicable, and the sentence shall not be executed until after the determination of the appeal.
