Can a grand jury foreman ask members of the jury who cannot act impartially to retire?

In People v. Jefferson, Supra, the validity of an indictment was upheld even though the foreman had failed to comply with Penal Code section 907 (now Pen.Code 939.5) directing that he ask members of the jury who could not act impartially to retire.

Penal Code section 935 permits, and Government Code section 26501 requires, the district attorney to attend and advise the grand jury but those statutes do not require the jury to request or accept that advice. The grand jury may act without reference to advice by the district attorney. (People v. Coleman, 83 Cal.App.2d 812, 189 P.2d 845.) The grand jury is also entitled to ask and receive advice from the superior court but it is not required to do so. (Pen.Code, 934.)