Being deployment-specific with instance folders

Flask provides yet another method for configuration, where we can efficiently manage deployment-specific parts. Instance folders allow us to segregate deployment-specific files from our version-controlled application. We know that configuration files can be separate for different deployment environments, such as development and production, but there are also many more files, such as database files, session files, cache files, and other runtime files. In this recipe, we will create an instance folder, which will act like a holder bin for such kinds of files.