code: func (s *RepositoriesService) ListStatuses(ctx context.Context, owner, repo, ref string, opt *ListOptions) ([]*RepoStatus, *Response, error) {
  	u := fmt.Sprintf("repos/%v/%v/commits/%v/statuses", owner, repo, url.QueryEscape(ref))
  	u, err := addOptions(u, opt)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	req, err := s.client.NewRequest("GET", u, nil)
  	if err != nil {
  		return nil, nil, err
  	}
  
  	var statuses []*RepoStatus
  	resp, err := s.client.Do(ctx, req, &statuses)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return statuses, resp, nil
  }
docs: // ListStatuses lists the statuses of a repository at the specified
  // reference. ref can be a SHA, a branch name, or a tag name.
  //
  // GitHub API docs: https://developer.github.com/v3/repos/statuses/#list-statuses-for-a-specific-ref