SECTION 7. HEADS OF DEPARTMENTS.
   At the head of each department there shall be a director, appointed by the City Manager, who shall have supervision and control of the department subject to the City Manager.
   Two or more departments may be headed by the same person and directors of departments may also serve as heads or chiefs of divisions. The City Manager may act as director of one or more departments, except that he may not act as Director of Finance or Director of Law.