In this exercise we are going to build a function that receives as a parameter an integer n and returns the nth Fibonacci number. In mathematics, the Fibonacci series is the infinite sequence of natural numbers that you can see on the slide:
0,1,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,1597
The sequence begins with 0 and 1, the following terms are always the sum of the previous two.