The Fibonacci sequence
0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 ...
is defined by the formula Fn = Fn-1 + Fn-2 for n ≥ 2 with F0 = 0 and F1 = 1. The Fibonacci numbers have many interesting properties and arise in numerous applications. For example, certain rhythmic pieces of music for the Indian instrument known as the tabla come in short strokes (1 beat) and long strokes (2 beats). How many difference ways can you fill up 8 beats with short and long strokes? The answer is the 34 (the 8+1st Fibonacci number).
You have to fill in the fib method to recursively return the nth fibonacci number.