A contract to make a will or devise, or not to revoke a will or devise, or to die intestate, if executed after January 1, 1983, can be established only by:

1. (1) Provisions of a will stating material provisions of the contract;
2. (2) An express reference in a will to a contract and extrinsic evidence proving the terms of the contract; or

3. (3) A writing signed by the decedent evidencing the contract.

   The execution of a joint will or mutual wills does not create a presumption of a contract not to revoke the will or wills.

(Acts 1982, No. 82-399, §2-701.)