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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 commit_comment(self, comment_id):
 """Get a single commit comment. :param int comment_id: (required), id of the comment used by GitHub :returns: :class:`RepoComment <github3.repos.comment.RepoComment>` if successful, otherwise None """

        url = self._build_url('comments', str(comment_id), base_url=self._api)
        json = self._json(self._get(url), 200)
        return RepoComment(json, self) if json else None