code: def is_archived(self, experiment, ignore_missing=True):
          
          if ignore_missing:
              if isinstance(self.config.experiments.get(experiment, True),
                            Archive):
                  return self.config.experiments.get(experiment, True)
          else:
              if isinstance(self.config.experiments[experiment], Archive):
                  return self.config.experiments[experiment]
docs: Convenience function to determine whether the given experiment has been
          archived already
  
          Parameters
          ----------
          experiment: str
              The experiment to check
  
          Returns
          -------
          str or None
              The path to the archive if it has been archived, otherwise None