No officer or employee of the Government may create or authorize an obligation in excess of the funds available, or in advance of appropriations (Anti-Deficiency Act, 31 U.S.C. 1341), unless otherwise authorized by law. Before executing any contract, the contracting officer shall-

(a) Obtain written assurance from responsible fiscal authority that adequate funds are available or

(b) Expressly condition the contract upon availability of funds in accordance with 32.703-2.