docs: def check_file_ids(self, rawfiles, cellpyfile):
          """Check the stats for the files (raw-data and cellpy hdf5).
  
          This function checks if the hdf5 file and the res-files have the same
          timestamps etc to find out if we need to bother to load .res -files.
  
          Args:
              cellpyfile (str): filename of the cellpy hdf5-file.
              rawfiles (list of str): name(s) of raw-data file(s).
  
  
          Returns:
              False if the raw files are newer than the cellpy hdf5-file
                  (update needed).
              If return_res is True it also returns list of raw-file_names as
                  second argument.
              """
  
          txt = "checking file ids - using '%s'" % self.filestatuschecker
          self.logger.info(txt)
  
          ids_cellpy_file = self._check_cellpy_file(cellpyfile)
  
          self.logger.debug(f"cellpyfile ids: {ids_cellpy_file}")
  
          if not ids_cellpy_file:
              # self.logger.debug("hdf5 file does not exist - needs updating")
              return False
  
          ids_raw = self._check_raw(rawfiles)
          similar = self._compare_ids(ids_raw, ids_cellpy_file)
  
          if not similar:
              # self.logger.debug("hdf5 file needs updating")
              return False
          else:
              # self.logger.debug("hdf5 file is updated")
              return True