input: def fibonacci(n: int) -> int:
      """ Calculate the nth Fibonacci number using recursion.
      >>> fibonacci(0)
      0
      >>> fibonacci(1)
      1
      >>> fibonacci(6)
      8
      """
      if n == 0:
          return 0
      elif n == 1:
          return 1
      else:
          return fibonacci(n - 1) + fibonacci(n - 2)
output:     if n == 0:
          return 0
      elif n == 1:
          return 1
      else:
          return fibonacci(n - 1) + fibonacci(n - 2)