input: 
  def use_file_system(file_sys, actions):
      """ Given an instance of the FileSystem class and a list of actions, perform the actions
      and return the results. The actions can include:
      - 'save': Save a task with specified data. The data should be a dictionary.
      - 'delete': Delete a task with the specified ID.
      - 'findById': Find and return the task data for the specified ID.
      - 'findByIds': Find and return a list of task data for the specified list of IDs.
      - 'allTaskData': Return a list of all task data.
      - 'taskData': Return the task data for the specified ID, or None if the data is not found.
  
      Example:
      fs = FileSystem({'taskDir': '~/jsub/'})
      actions = [
          {'action': 'save', 'data': {'name': 'Task1', 'description': 'First task'}},
          {'action': 'save', 'data': {'id': 1, 'name': 'Task1', 'status': 'completed'}},
          {'action': 'findById', 'id': 1},
          {'action': 'delete', 'id': 1},
          {'action': 'allTaskData'}
      ]
      results = use_file_system(fs, actions)
      print(results)
      # Output: [None, None, {'id': 1, 'name': 'Task1', 'status': 'completed'}, None, []]
      """
  
output:     results = []
      for action in actions:
          if action['action'] == 'save':
              file_sys.save(action['data'])
              results.append(None)
          elif action['action'] == 'delete':
              file_sys.delete(action['id'])
              results.append(None)
          elif action['action'] == 'findById':
              results.append(file_sys.findById(action['id']))
          elif action['action'] == 'findByIds':
              results.append(file_sys.findByIds(action['ids']))
          elif action['action'] == 'allTaskData':
              results.append(file_sys.allTaskData())
          elif action['action'] == 'taskData':
              results.append(file_sys.taskData(action['id']))
      return results