docs: def event(self, event_name):
          """Register an event that occurred during processing of a task of the given
          type.
  
          Args:     event_name: str         A name for a type of events. Events of the
          same type are displayed as         a single entry and a total count of
          occurences.
  
          """
          self._event_dict.setdefault(event_name, 0)
          self._event_dict[event_name] += 1
          self._log_progress_if_interval_elapsed()