def add_issue_comment(self, issue_id_or_key, content, extra_request_params={}):
        """
        client = BacklogClient("your_space_name", "your_api_key")
        client.add_issue_comment("YOUR_PROJECT-999", u"or ... else e.")
        """
        request_params = extra_request_params
        request_params["content"] = content
        return self.do("POST", "issues/{issue_id_or_key}/comments",
                       url_params={"issue_id_or_key": issue_id_or_key},
                       request_params=request_params,
                       )
client = BacklogClient("your_space_name", "your_api_key")
        client.add_issue_comment("YOUR_PROJECT-999", u"or ... else e.")