code: def top_submitters(self, num):
          
          num = min(num, len(self.submitters))
          if num <= 0:
              return ''
  
          top_submitters = sorted(
              iteritems(self.submitters),
              key=lambda x: (-sum(y.score for y in x[1]),
                             -len(x[1]), str(x[0])))[:num]
  
          retval = self.post_header.format('Top Submitters\' Top Submissions')
          for (author, submissions) in top_submitters:
              retval += '1. {}, {} submission{}: {}\n'.format(
                  self._points(sum(x.score for x in submissions)),
                  len(submissions),
                  's' if len(submissions) != 1 else '', self._user(author))
              for sub in sorted(
                      submissions, key=lambda x: (-x.score, x.title))[:10]:
                  title = self._safe_title(sub)
                  if sub.permalink in sub.url:
                      retval += tt('  1. {}').format(title)
                  else:
                      retval += tt('  1. [{}]({})').format(title, sub.url)
                  retval += ' ({}, [{} comment{}]({}))\n'.format(
                      self._points(sub.score), sub.num_comments,
                      's' if sub.num_comments != 1 else '',
                      self._permalink(sub))
              retval += '\n'
          return retval
docs: Return a markdown representation of the top submitters.