Write a function that will find the nth Fibonacci number, where n is given by the user: A Fibonacci sequence is a sequence for which the first element is equal to 0, the second one is 1, and each next one is the sum of the previous two. Fn = for n = 0; for n = 1; Fn-1+ Fn-2 for n > 1. 0 1 Below are the few first numbers of the fibonacci sequence: 0, 1, 1, 2, 3, 5, 8, 13, 21...