go =>
  take(15, $fib_gen(0,1), $T-[], _G),
  println(T).

take( 0, Next, Z-Z, Next).
take( N, Next, [A|B]-Z, NZ):- N>0, !, next( Next, A, Next1),
  N1 is N-1,
  take( N1, Next1, $B-Z, NZ).

next( fib_gen(A,B), A, fib_gen(B,C)):- C is A+B.