input: 
  from typing import Dict, List, Optional
  
  class FileSystem(object):
      """
      Provides methods for saving, deleting, finding, and retrieving task data.
      
      To use this class, create an instance with a dictionary that includes a 'taskDir' key
      specifying the directory where task data should be stored.
      
      Example usage:
      >>> fs = FileSystem({'taskDir': '~/tasks/'})
      >>> fs.save_task({'name': 'Task1', 'description': 'Do something'})
      >>> fs.find_by_id('1')
      {'id': '1', 'name': 'Task1', 'description': 'Do something'}
      >>> fs.delete_task('1')
      >>> fs.find_by_id('1')
      None
      """
      def __init__(self, param: Dict[str, str]):
          self.__jsub_dir = os.path.expanduser(param.get('taskDir', '~/jsub/'))
          self.__logger = logging.getLogger('JSUB')
          self.__json_format = param.get('format', 'compact')
  
      def save_task(self, data: Dict[str, str]):
          if 'id' not in data:
              safe_mkdir(self.__jsub_dir)
              data['id'] = self.__new_task_id()
          safe_mkdir(os.path.join(self.__jsub_dir, str(data['id']), 'taskInfo'))
          task_path = os.path.join(self.__jsub_dir, str(data['id']), 'taskInfo', 'repo')
          data_str = self.__json_str(data)
          with open(task_path, 'a+') as f:
              fcntl.flock(f, fcntl.LOCK_EX)
              f.seek(0)
              f.truncate()
              f.write(data_str)
  
      def delete_task(self, task_id: str):
          safe_rmdir(os.path.join(self.__jsub_dir, str(task_id)))
  
      def find_by_id(self, task_id: str) -> Optional[Dict[str, str]]:
          return self.task_data(task_id)
  
      def find_by_ids(self, task_ids: List[str]) -> List[Dict[str, str]]:
          all_data = []
          for task_id in task_ids:
              try:
                  td = self.task_data(task_id)
                  all_data.append(td)
              except RepoReadError as e:
                  self.__logger.debug(e)
          return all_data
  
      def all_task_data(self, order: str = 'asc') -> List[Dict[str, str]]:
          task_ids = [d for d in os.listdir(self.__jsub_dir) if os.path.isdir(os.path.join(self.__jsub_dir, d))]
          task_ids.sort(key=int, reverse=(order == 'desc'))
          return self.find_by_ids(task_ids)
  
      def task_data(self, task_id: str) -> Optional[Dict[str, str]]:
          safe_mkdir(os.path.join(self.__jsub_dir, str(task_id), 'taskInfo'))
          task_path = os.path.join(self.__jsub_dir, str(task_id), 'taskInfo', 'repo')
          with open(task_path, 'a+') as f:
              fcntl.flock(f, fcntl.LOCK_EX)
              f.seek(0)
              data_str = f.read()
          try:
              return json.loads(data_str)
          except ValueError as e:
              raise RepoReadError(f'JSON decode error on task {task_id}: {e}')
  
      def __new_task_id(self) -> str:
          task_ids = [int(d) for d in os.listdir(self.__jsub_dir) if os.path.isdir(os.path.join(self.__jsub_dir, d))]
          if not task_ids:
              return '1'
          task_ids.sort(key=int, reverse=True)
          return str(task_ids[0] + 1)
  
      def __json_str(self, data: Dict[str, str]) -> str:
          if self.__json_format == 'pretty':
              return json.dumps(data, indent=2)
          return json.dumps(data, separators=(',', ':'))
  
output:     
      def update_task(self, task_id: str, data: Dict[str, str]):
          task_path = os.path.join(self.__jsub_dir, str(task_id), 'taskInfo', 'repo')
          with open(task_path, 'a+') as f:
              fcntl.flock(f, fcntl.LOCK_EX)
              f.seek(0)
              existing_data = f.read()
              if existing_data:
                  existing_data = json.loads(existing_data)
                  existing_data.update(data)
                  data_str = self.__json_str(existing_data)
              else:
                  data_str = self.__json_str(data)
              f.truncate()
              f.write(data_str)
  