'Get a single comment by its id.
The catch here is that id is NOT a simple number to obtain. If
you were to look at the comments on issue #15 in
sigmavirus24/Todo.txt-python, the first comment\'s id is 4150787.
:param int id_num: (required), comment id, see example above
:returns: :class:`IssueComment <github3.issues.comment.IssueComment>`'

def comment(self, id_num):

    json = None
    if (int(id_num) > 0):
        (owner, repo) = self.repository
        url = self._build_url(u'repos', owner, repo, u'issues', u'comments', str(id_num))
        json = self._json(self._get(url), 200)
    return self._instance_or_null(IssueComment, json)
