Define project-wide constants inside your custom package

## Why you would want to define project-wide constants

There are some "basic facts" about a project that you might want to be able to leverage project-wide. One example of this might be data source files (CSVs, Excel spreadsheets) that you might want convenient paths to (see: Use pyprojroot to define relative paths to the project root).

## How do you define project-wide constants

Assuming you have a custom source package defined (see: Place custom source code inside a lightweight package), this is not difficult at all.

Ensure that you have a constants.py, or else something named sanely, and place all of your constants in there as variables. (Paths should probably go in a paths.py file.)

Then, import the constants (or paths) into your source project anywhere you need it!