docs: def clear(self, tag=None):
          """
          Deletes scheduled jobs marked with the given tag, or all jobs
          if tag is omitted.
  
          :param tag: An identifier used to identify a subset of
                      jobs to delete
          """
          if tag is None:
              del self.jobs[:]
          else:
              self.jobs[:] = (job for job in self.jobs if tag not in job.tags)