The Fib object provides a method for computing Fibonacci numbers.
Fib
Compute the n-th Fibonacci number, e.g., f(4) = f(3) + f(2) = 2 + 1 = 3. It uses the Naive Approach, see link for more efficient approaches.
the number to compute (for n >= 0)
https://www.geeksforgeeks.org/program-for-nth-fibonacci-number/