input: Write a python function to calculate the nth Fibonacci number recursively.
  assert Fibonacci(0) == 0
  assert Fibonacci(1) == 1
  assert Fibonacci(5) == 5
  assert Fibonacci(10) == 55
output: def Fibonacci(n):
      if n == 0:
          return 0
      elif n == 1:
          return 1
      else:
          return Fibonacci(n - 1) + Fibonacci(n - 2)