Add two inputs together

### User story
As an analytical code developer, I want a function that adds two numbers together, 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

The issue names no file, entry point, or test. First inspect the repository to find where analytical functions belong and determine whether Python or R is intended; done means the two-number addition runs without error, has the requested documentation, meets the requirements, and is ready for peer review.

Written by the indexing model from the issue text.