text: const fibonacci = n => {
    if (n < 2 || typeof n !== 'number') return;
    const fib = [0, 1];
    for (let i = 0; i < n; i++) fib.push(fib[fib.length - 1] + fib[fib.length - 2]);
    return fib[fib.length - 2];
  };
  console.log(fibonacci(9));