After saving our previously discussed two-line code, click on Run and then on Run Module F5. If there is no error, the following line will appear. By the way, if we click on Run before we save the program, we will be asked to save it:

>>>===========RESTART ==================

To check whether the pv_f() function is present in the memory, we type dir(), as shown in the following code:

>>>dir()
['__builtins__', '__doc__', '__file__', '__loader__', '__name__', '__package__', 'pv_f']
>>>

Now, we can execute this Python program by entering a set of three input values, as shown in the following code:

>>>pv_f(100,0.1,1)
90.9090909090909

As we discussed before, we could use the key word method to input values. After we quit and relaunch Python, the pv_f() function will be no longer available.