At the time set for the examination of the case, if the public offense is a felony punishable with death, or is a felony to which the defendant has not pleaded guilty in accordance with Section 859a of this code, then, if the defendant requires the aid of counsel, the magistrate must allow the defendant a reasonable time to send for counsel, and may postpone the examination for not less than two nor more than five days for that purpose. The magistrate must, immediately after the appearance of counsel, or if, after waiting a reasonable time therefor, none appears, proceed to examine the case; provided, however, that a defendant represented by counsel may when brought before the magistrate as provided in Section 858 or at any time subsequent thereto, waive the right to an examination before such magistrate, and thereupon it shall be the duty of the magistrate to make an order holding the defendant to answer, and it shall be the duty of the district attorney within 15 days thereafter, to file in the superior court of the county in which the offense is triable the information; provided, further, however, that nothing contained herein shall prevent the district attorney nor the magistrate from requiring that an examination be held as provided in this chapter.