The bonds or other securities issued by a political subdivision are valid, binding, and incontestable after:

1. (1) approval by the attorney general;
2. (2) registration by the comptroller; and
3. (3) purchase by and delivery to the board.

Amended by Acts 1987, 70th Leg., ch. 1103, Sec. 1, eff. Sept. 1, 1987.