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