I. Write a scheme macro (firstNon0 ), which evaluates the one by one until one of them evaluates to a non-0 value. As soon as it finds an which evaluates to a non-zero value, firstNon0 stops and returns that value. If all of the s evaluate to 0, firstNon0 should return 0. If you prefer, your macro can take more than three s

II. Write a scheme function (tribonacci n). The tribonacci numbers T_i are defined as T₀ = T₁ = 0, T₂ = 1, and T_N = T_N-1 + T_N-2 + T_N-3. (tribonacci n) should return T_n

IV. Write a definition in Prolog for the predicate trib(N, T) which is true if T is the Nth tribonacci number, as defined above.