Upon receipt of a proposed initiative measure, and before giving it a serial number, the secretary of state shall submit a copy thereof to the office of the code reviser and give notice to the sponsor of such transmittal. Upon receipt of the measure, the assistant code reviser to whom it has been assigned may confer with the sponsor and shall within seven working days from its receipt, review the proposal and recommend to the sponsor such revision or alteration of the measure as may be deemed necessary and appropriate. The recommendations of the code reviser's office are advisory only, and the sponsor may accept or reject them in whole or in part. The code reviser shall issue a certificate of review certifying that he or she has reviewed the measure and that any recommendations have been communicated to the sponsor. The certificate must be issued whether or not the sponsor accepts such recommendations. Within fifteen working days after notification of submittal of the proposed measure to the code reviser's office, the sponsor, if he or she desires to proceed with sponsorship, shall file the measure together with the certificate of review with the secretary of state for assignment of a serial number, and the secretary of state shall then submit to the code reviser's office a certified copy of the measure filed. Upon submission of the proposal to the secretary of state for assignment of a serial number, the secretary of state shall refuse to make such assignment unless the proposal is accompanied by a certificate of review.