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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def top_submissions(self):
 """Return a markdown representation of the top submissions."""

        num = min(10, len(self.submissions))
        if num <= 0:
            return ''

        top_submissions = sorted(
            [x for x in self.submissions.values() if self.distinguished or
             x.distinguished is None],
            key=lambda x: (-x.score, -x.num_comments, x.title))[:num]

        if not top_submissions:
            return ''

        retval = self.post_header.format('Top Submissions')
        for sub in top_submissions:
            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 += ' by {} ({}, [{} comment{}]({}))\n'.format(
                self._user(sub.author), self._points(sub.score),
                sub.num_comments, 's' if sub.num_comments != 1 else '',
                self._permalink(sub))
        return tt('{}\n').format(retval)