input: def fibonacci_seq(n: int) -> int:
      """Generate the nth Fibonacci number.
      >>> fibonacci_seq(0)
      0
      >>> fibonacci_seq(1)
      1
      >>> fibonacci_seq(2)
      1
      >>> fibonacci_seq(5)
      5
      """
      if n == 0:
          return 0
      elif n == 1:
          return 1
      else:
          return fibonacci_seq(n-1) + fibonacci_seq(n-2)
output:     if n == 0:
          return 0
      elif n == 1:
          return 1
      else:
          return fibonacci_seq(n-1) + fibonacci_seq(n-2)