The preceding two sections show the two ways to activate our program, that is, from a Python editor or using the import function. Usually, the choice should depend on a user's preference. However, while debugging, activating our program from our Python editor is much better than the second method. If we use the second method, our program is not updated as we normally expect.

The following example contains a typo since we use both r (lower case) and R (capital letter) in the program (assume that we save it under C:\Python33 with the name test02.py):

def pv_f(fv,r,n):
    return fv/(1+R)**n   # a typo of r

After issuing from test02 import * and calling the function, we will see an error message, as shown in the following code:

>>>from test02 import *
>>>pv_f(100,0.1,1)
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    pv_f(100,0.1,1)
  File ".\test02.py", line 3, in pv_f
    return fv/(1+R...