on the inquiry instituted by a grand jury than to protect from delay the progress of the trial after an indictment has been found." Id. at 327, 60 S. Cr. at 542; see also Di Bella v. United States. 369 U.S. 121, 124, 82 S.O. 654, 656-57, 7 L.Pd.2d 614 (1962) ("This insistence on finality and prohib