Using environment variables (from GitLab) in local development

Hey there!

I'm messing around with a Flask project I have on GitLab, with some plans to host it on a Heroku server. I'm at the point where using some environment variables (for API keys, etc.) would be super helpful, so I'm looking at GitLab's environment variable tools. Maybe I'm just not seeing it, but is there a way I can use my environment variables during local development as well as in production?