Section 3(n) of the Act defines the word ``officer'' and it is this definition which must be used as a guide in determining what particular positions in a labor organization are to be filled in the manner prescribed in the Act. For purposes of the Act, ``officer'' means ``any constitutional officer, any person authorized to perform the functions of president, vice president, secretary, treasurer, or other executive functions of a labor organization, and any member of its executive board or similar governing body.''