Function fib2

test/README.example.spec.ts:1376–1379

(n: number)

      });

    const fib2 = (n: number): Effected<never, number> => {
      if (n <= 1) return Effected.of(n);
      return fib2(n - 1).andThen((a) => fib2(n - 2).andThen((b) => a + b));
    };

    const fib3 = (n: number): Effected<never, number> => {
      if (n <= 1) return Effected.from(() => n);