code: func (s *UsersService) ListFollowers(ctx context.Context, user string, opt *ListOptions) ([]*User, *Response, error) {
  	var u string
  	if user != "" {
  		u = fmt.Sprintf("users/%v/followers", user)
  	} else {
  		u = "user/followers"
  	}
  	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 users []*User
  	resp, err := s.client.Do(ctx, req, &users)
  	if err != nil {
  		return nil, resp, err
  	}
  
  	return users, resp, nil
  }
docs: // ListFollowers lists the followers for a user. Passing the empty string will
  // fetch followers for the authenticated user.
  //
  // GitHub API docs: https://developer.github.com/v3/users/followers/#list-followers-of-a-user