code: def _is_pickle_valid(self):
          
          if not os.path.exists(self._pickle_file):
              return False
          else:
              file_mtime = os.path.getmtime(self.logfile)
              pickle_mtime = os.path.getmtime(self._pickle_file)
              if file_mtime > pickle_mtime:
                  return False
          return True
docs: Logic to decide if the file should be processed or just needs to
          be loaded from its pickle data.