Ipython 隐式类型错误：'；十进制。十进制'；对象不能解释为整数

我很难理解为什么Jupyter笔记本中的此功能显然失败了，但IPython外壳中却没有：

def present_value( r, n, fv = None, pmt = None ):
    '''
    Function to compute the Present Value based on interest rate and 
    a given future value. 

    Arguments accepted
    ------------------
       *   r = interest rate,
               which should be given in its original percentage, eg. 
               5% instead of 0.05

       *   n = number of periods for which the cash flow,
               either as annuity or single flow from one present value

       *  fv = future value in dollars,
               if problem is annuity based, leave this empty

       * pmt = each annuity payment in dollars,
               if problem is single cash flow based, leave this empty
    '''
    original_args = [r, n, fv, pmt]
    dec_args      = [Decimal( arg ) if arg != None
                                  else arg
                                  for  arg in original_args
                                  ]
    if dec_args[3] == None:
        return dec_args[2] / ( ( 1 + ( dec_args[0] / 100 ) )**dec_args[1] )

    elif dec_args[2] == None:
        #                     annuity_length = range( 1, dec_args[1] + 1 )
        #                     Not allowed to add a Decimal object
        #                     with an integer and to use it
        #                     in the range() function,
        #                     so we dereference the integer from original_args
        annuity_length = range( 1, original_args[1] + 1 )
        #                     Apply discounting to each annuity payment made
        #                     according to number of years left till end
        all_compounded_pmt = [dec_args[3] * ( 1 / ( ( 1 + dec_args[0] / 100 ) ** time_left ) ) \
                              for time_left in annuity_length
                              ]
        return sum( all_compounded_pmt )

当我使用functions import*中的

，导入该函数所在的模块，名为
functions.py
，然后执行
present\u value（r=7，n=35，pmt=11000）
，我得到了错误：

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-93-c1cc587f7e27> in <module>()
----> 1 present_value(r=7, n=35, pmt = 11000)

/path_to_file/functions.py in present_value(r, n, fv, pmt)
     73     if dec_args[3] == None:
     74         return dec_args[2]/((1 + (dec_args[0]/100))**dec_args[1])
---> 75 
     76     elif dec_args[2] == None:
     77 #        annuity_length = range(1, dec_args[1]+1)

TypeError: 'decimal.Decimal' object cannot be interpreted as an integer

有谁能帮我解决这个令人费解且晦涩难懂的问题吗？
IIRC你是通过重启内核解决的吗？是的，我在IPython Github上发布这篇文章时，得到了帮助我的人的大力帮助：插入
imp.reload（）吗
进入IPython笔记本或类似的帮助允许我不重新启动内核吗？什么是好的做法？这要看情况而定。它甚至可能取决于您的Python版本。模块不应该是可重新加载的，但对于大多数模块来说，它是可以工作的。这就是Python的“我们在成年人之间”哲学。如果您想发疯并尝试imp.reload（），它可能会起作用，如果不起作用，那么它就不是一个真正的bug。
In [42]: functions.present_value(r=7, n=35, pmt = 11000)
Out[42]: Decimal('142424.39530474029537')