code: def get_apps_to_backup(self):
          
          # Instantiate the app db
          app_db = appsdb.ApplicationsDatabase()
  
          # If a list of apps to sync is specify, we only allow those
          # Or we allow every supported app by default
          apps_to_backup = self._config.apps_to_sync or app_db.get_app_names()
  
          # Remove the specified apps to ignore
          for app_name in self._config.apps_to_ignore:
              apps_to_backup.discard(app_name)
  
          return apps_to_backup
docs: Get the list of applications that should be backed up by Mackup.
  
          It's the list of allowed apps minus the list of ignored apps.
  
          Returns:
              (set) List of application names to back up