It shall be the duty of all officers and employees of any such city to aid in all proper ways of carrying out the provisions of this chapter, and such rules and regulations as may, from time to time, be prescribed by the commission thereunder and to afford the commission, its members and employees, all reasonable facilities and assistance to inspect all books, papers, documents and accounts applying or in any way appertaining to any and all offices, places, positions and employments, subject to civil service, and also to produce said books, papers, documents and accounts, and attend and testify, whenever required so to do by the commission or any commissioner.