input: def fibonacci(n: int) -> int:
      """Generate Fibonacci numbers using a recursive approach.
      >>> fibonacci(1)
      1
      >>> fibonacci(2)
      1
      >>> fibonacci(10)
      55
      """
output:     if n <= 0:
          return 0
      elif n == 1:
          return 1
      else:
          return fibonacci(n - 1) + fibonacci(n - 2)