Your question is Nth Fibonacci Number. Start with the requirements on the right.
Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.
Given a non-negative integer n, return the nth Fibonacci number. The Fibonacci sequence is defined as F(0) = 0, F(1) = 1, and F(n) = F(n - 1) + F(n - 2) for n >= 2. The function should return a single integer.
def fibonacci(n):