code: func (c *Client) GetUser(name string) (services.User, error) {
  	if name == "" {
  		return nil, trace.BadParameter("missing username")
  	}
  	out, err := c.Get(c.Endpoint("users", name), url.Values{})
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  	user, err := services.GetUserMarshaler().UnmarshalUser(out.Bytes(), services.SkipValidation())
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  	return user, nil
  }
docs: // GetUser returns a list of usernames registered in the system