How can I detect Heroku's environment?

How can I detect Heroku's environment?

python django deployment heroku environment

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Angular app on Heroku built using Webpack - Environment variables?

angularjs variables heroku webpack environment

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Setting a grails app environment in heroku?

grails heroku environment

heroku

Trouble deciding whether to use autoenv or python dotenv

python heroku flask environment-variables environment

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Ember-CLI app deployed to heroku with environment=production loses global app namespace

heroku ember.js ember-cli environment

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Set up local development environment for heroku facebook app

facebook heroku local environment

heroku