code: def add_labels_to_pr(repo: GithubRepository,
                       pull_id: int,
                       *labels: str,
                       override_token: str = None) -> None:
      
      url = ("https://api.github.com/repos/{}/{}/issues/{}/labels"
             "?access_token={}".format(repo.organization,
                                       repo.name,
                                       pull_id,
                                       override_token or repo.access_token))
      response = requests.post(url, json=list(labels))
  
      if response.status_code != 200:
          raise RuntimeError(
              'Add labels failed. Code: {}. Content: {}.'.format(
                  response.status_code, response.content))
docs: References:
          https://developer.github.com/v3/issues/labels/#add-labels-to-an-issue