Subtract one input from another

### User story
As an analytical code developer, I want a function that subtracts one number from another, so that I can practice using Git.

### Definition of done
- [ ] Runs without error
- [ ] Fully meets the user requirements
- [ ] Documented using a [docstring for python](https://peps.python.org/pep-0257/) or [roxygen2 comment for R](https://cran.r-project.org/web/packages/roxygen2/vignettes/roxygen2.html)
- [ ] Peer reviewed and updated if needed

No source file, test, or language is specified; first locate the exercise entry point and determine whether it uses Python or R. Add a function that subtracts one number from another, document it with the required docstring or roxygen2 comment, and verify it runs without error and meets the user story.

Written by the indexing model from the issue text.