code: def basic_stats(self):
          
          comment_score = sum(comment.score for comment in self.comments)
          if self.comments:
              comment_duration = (self.comments[-1].created_utc -
                                  self.comments[0].created_utc)
              comment_rate = self._rate(len(self.comments), comment_duration)
          else:
              comment_rate = 0
  
          submission_duration = self.max_date - self.min_date
          submission_rate = self._rate(len(self.submissions),
                                       submission_duration)
          submission_score = sum(sub.score for sub in self.submissions.values())
  
          values = [('Total', len(self.submissions), len(self.comments)),
                    ('Rate (per day)', '{:.2f}'.format(submission_rate),
                     '{:.2f}'.format(comment_rate)),
                    ('Unique Redditors', len(self.submitters),
                     len(self.commenters)),
                    ('Combined Score', submission_score, comment_score)]
  
          retval = 'Period: {:.2f} days\n\n'.format(submission_duration / 86400.)
          retval += '||Submissions|Comments|\n:-:|--:|--:\n'
          for quad in values:
              retval += '__{}__|{}|{}\n'.format(*quad)
          return retval + '\n'
docs: Return a markdown representation of simple statistics.