code: function fetchGitHub(url) {
    return fetch(url).then(res => {
      if (res.status === STATUS_NOT_FOUND) {
        throw new Error('USER_NOT_FOUND');
      } else if (res.status !== STATUS_OK) {
        throw new Error('CANNOT_FETCH_DATA');
      }
      return res.text();
    });
  }
docs: Fetch HTML from GitHub
  
  @param {string} url - URL
  @return {Promise<string, Error>}