func_code: def fibonacci(n):
      total = 0
      n0 = 0
      n1 = 1
      if n == 0:
          total = n0
          return total
      elif n == 1:
          total = n1
          return total
      else:
          while total < n:
              n = n0 + n1
              n0 = n1
              n1 = n
              total = total + 1
          return total