A recursive function is a function that can call itself. Fibonacci numbers are defined:F(n) = F(n-1) + F(n-2) with F(0) = 0 and F(1) = 1, giving the sequence 0, 1, 1, 2, 3, 5, 8, 13, ... which you're probably familiar with.Here's how we can write that in python:def fib(n): if n <= 0: # The base and invalid case return 0 elif n == 1: # Another base case return 1 else: # The recursive definition return fib(n-1) + fib(n-2) print(fib(6)) # Prints 8 There are a few things to consider. Why do we we need the 'return 0' and 'return 1' statements? What's the invalid case? Is this the best way to find the nth Fibonacci number?