Writing a program – the empty shell method

To vividly describe this method, we call it the empty shell method. The method works like this: generate an empty shell first and test it, then add one line and test it. If there is no error, add one more line and test the program. Repeat this procedure until you finish the whole program. The CND function is used as an example in the following case:

1. After launching Python, click on File then New Window Ctrl + N. Generate the following empty shell:

   def CND(x):
       return x
   

2. Click on File | Save; for example, save it as cnd.py.
3. Click on Run and then click on Run from module F5. The following line will appear:

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

4. To test our program, we will enter various values. If we enter 1, the output would be 1. If we enter 5, then the output will be 5, as shown in the following example:

   >>>CND(1)
   1
   

5. We add one line as shown in the following code:

   def CND(x):
       (a1,a2,a3,a4,a5)=(0.31938153,-0.356563782...