whatever the default extension needed by the library im using. i dont have a horse in this race

yaml

same for html instead of htm.

On Linux, there is no reason to use 3 characters extension as the max path length is 4096 characters, so I’ll just use the most descriptive filename and extension. I can see the need to use the shortest extension possible on windows though with its limited 256 max path length.

config_file.yaml embrace the snake case