Ubuntu default program setting

To open the python file on the Linux system, there was inconvenient to open with Vscode because ubuntu basically opened the file with a text editor.

There was a default program setting tab, but it was meaningless because there was no other option in the checklist.
The solution is simple

1. Right-click on the file and open the properties
   
2. Click the open with… option, which is on the right side of the three options.
   
3. Click the application which you want to open with, and Set the program to default with the Set as default button.
   
4. 끝
   

Ps. I can not understand why the default program option in the setting exists.