input: Write a function to recursively calculate the Fibonacci numbers up to a given number. If the given number is 0, return 0. If the given number is 1, return 1. Otherwise, return the sum of the previous two Fibonacci numbers.
  def Fibonacci(n): 
  	if n==0: 
  		return 0
  	if n==1: 
  		return 1
  	else: 
  		return Fibonacci(n-1)+Fibonacci(n-2)
  assert Fibonacci(0)==0
  assert Fibonacci(1)==1
  assert Fibonacci(5)==5
  assert Fibonacci(10)==55
  assert Fibonacci(20)==6765
output: def Fibonacci(n): 
  	if n==0: 
  		return 0
  	if n==1: 
  		return 1
  	else: 
  		return Fibonacci(n-1)+Fibonacci(n-2)