code: def deploy(app_id, version, promote, quiet):
      # type: (str, str, bool, bool) -> None
      
      gae_app = GaeApp.for_branch(git.current_branch().name)
  
      if gae_app is None and None in (app_id,  version):
          msg = (
              "Can't find an AppEngine app setup for branch <35>{}<32> and"
              "--project and --version were not given."
          )
          log.err(msg, git.current_branch().name)
          sys.exit(1)
  
      if version is not None:
          gae_app.version = version
  
      if app_id is not None:
          gae_app.app_id = app_id
  
      gae_app.deploy(promote, quiet)
docs: Deploy the app to AppEngine.
  
      Args:
          app_id (str):
              AppEngine App ID. Overrides config value app_id if given.
          version (str):
              AppEngine project version. Overrides config values if given.
          promote (bool):
              If set to **True** promote the current remote app version to the one
              that's being deployed.
          quiet (bool):
              If set to **True** this will pass the ``--quiet`` flag to gcloud
              command.