code: def get_app_env():
      
      app, env = None, get_env()
      if "app" in os.environ:
          app = os.environ["app"].lower()
          if ":" in app:
              app, env = os.environ["app"].split(":", 2)
              set_env(env)
      return app, env
docs: if the app and the envi are passed in the command line as 'app=$app:$env'
      :return: tuple app, env