code: def fsync(self, file_des):
          
          # Throw an error if file_des isn't valid
          if 0 <= file_des < NR_STD_STREAMS:
              self.filesystem.raise_os_error(errno.EINVAL)
          file_object = self.filesystem.get_open_file(file_des)
          if self.filesystem.is_windows_fs:
              if (not hasattr(file_object, 'allow_update') or
                      not file_object.allow_update):
                  self.filesystem.raise_os_error(
                      errno.EBADF, file_object.file_path)
docs: Perform fsync for a fake file (in other words, do nothing).
  
          Args:
              file_des: The file descriptor of the open file.
  
          Raises:
              OSError: file_des is an invalid file descriptor.
              TypeError: file_des is not an integer.