code: func (s *UsersService) ListAll(ctx context.Context, opt *UserListOptions) ([]*User, *Response, error) {
  	u, err := addOptions("users", 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: // ListAll lists all GitHub users.
  //
  // To paginate through all users, populate 'Since' with the ID of the last user.
  //
  // GitHub API docs: https://developer.github.com/v3/users/#get-all-users