docs: def issue_comments(self, issue_id_or_key, extra_query_params={}):
          """
          client = BacklogClient("your_space_name", "your_api_key")
          client.issue_comments("YOUR_PROJECT-999")
          """
          return self.do("GET", "issues/{issue_id_or_key}/comments",
                          url_params={"issue_id_or_key": issue_id_or_key},
                          query_params=extra_query_params
                          )