How do I import my own custom swift file into a project?

I have a small swift file with some extensions and helper functions that I like to use in all of my projects. It is platform-agnostic. Right now, I've been pasting a separate copy of the file into all of my projects whenever I need to use it. This is obviously not ideal because if I need to modify the file, then I have to update all of the copies floating around in each of my projects.

How to I import a file from outside my project into my project without making a separate copy?

I'm coming from Python where you could simply write import [module name] at the top of your file and it would import that module into your script.

Here's a link to the file in case anyone's interested.

You can compose this file into an actual module and import it exactly as you would in Python, the Swift Package Manager helps with this.