The Fibonacci Sequence is computed as
f(n) = f(n-1) + f(n-2). We must define two base case values:
f(0) = 0 and
f(1) = 1.
Thus, the first values of this sequence are: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, etc.
Your task is to write a function
fib which takes a single number
n and returns
f(n) as defined above by the Fibonacci Sequence.