lab recursive method

Write a recursive method to compute Fibonacci series.

Hint:

fib(n)=fib(n-1)+fib(n-2)

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, ...

測試第九個是否為21