Get the :class:`rtcclient.models.Comment` object by its id

        Note: the comment id starts from 0

        :param comment_id: the comment id (integer or equivalent string)
        :return: the :class:`rtcclient.models.Comment` object
        :rtype: rtcclient.models.Comment

def getCommentByID(self, comment_id):
        """Get the :class:`rtcclient.models.Comment` object by its id

        Note: the comment id starts from 0

        :param comment_id: the comment id (integer or equivalent string)
        :return: the :class:`rtcclient.models.Comment` object
        :rtype: rtcclient.models.Comment
        """

        # check the validity of comment id
        try:
            if isinstance(comment_id, bool):
                raise ValueError()
            if isinstance(comment_id, six.string_types):
                comment_id = int(comment_id)
            if not isinstance(comment_id, int):
                raise ValueError()
        except (ValueError, TypeError):
            raise exception.BadValue("Please input valid comment id")

        comment_url = "/".join([self.url,
                                "rtc_cm:comments/%s" % comment_id])
        try:
            return Comment(comment_url,
                           self.rtc_obj)
        except HTTPError:
            self.log.error("Comment %s does not exist", comment_id)
            raise exception.BadValue("Comment %s does not exist" % comment_id)