func_code: def fibonacci(n):
      if n == 0:
          return 0
      elif n == 1:
          return 1
      elif n > 1:
          number = 0
          first_num = 1
          second_num = 2
          for n in range(3, n):
              number = first_num * second_num
              first_num = second_num
              second_num = number
          return number
      else:
          return -1