(1) When a notice is required to be given to directors under this code, or the charter or bylaws of any state bank, a waiver thereof in writing, signed by the person entitled to said notice, either before or after the time stated therein, shall be deemed equivalent thereto.
(2) If the vote of directors at a meeting thereof is required or permitted to be taken in connection with any corporate action by any section of this code, the meeting and vote of directors may be dispensed with, if all of the directors who would have been entitled to vote upon the action if such meeting were held consent in writing to such corporate action being taken.
(3) In the event that the action that is consented to is such as would have required the filing of a certificate under any of the other sections of this code if such action had been voted upon by the directors at a meeting thereof, the certificate filed under such other section shall state that written consent has been given under this section.