input: 
  def fibonacci(n: int) -> int:
      """
      Calculate the nth Fibonacci number using a basic recursive algorithm.
      >>> fibonacci(6)
      8
      >>> fibonacci(0)
      0
      >>> fibonacci(1)
      1
      >>> fibonacci(10)
      55
      """
      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)