The codebase is designed with modular components to facilitate reuse, testing and maintenance

think about https://en.wikipedia.org/wiki/Separation_of_concerns
> separation of concerns (SoC) is the design principle of organizing a [codebase](https://en.wikipedia.org/wiki/Codebase) into distinct sections – each addressing a single [concern](https://en.wikipedia.org/wiki/Concern_(computer_science)). SoC is the design principle that guides [modular programming](https://en.wikipedia.org/wiki/Modular_programming).

## Examples

Check this resource: https://carpentries-incubator.github.io/better-research-software/05-code-structure.html