The right of a person to a pension, an annuity or a retirement allowance, to the return of contributions, the pension, annuity or retirement allowance itself, any optional benefit, any other right accrued or accruing to any person under the provisions of this chapter, and the moneys in the fund created under this chapter shall not be subject to execution, garnishment, attachment, or any other process whatsoever, whether the same be in actual possession of the person or be deposited or loaned and shall be unassignable except as in this chapter specifically provided.