code: func (a *Agent) ServiceDeregister(serviceID string) error {
  	r := a.c.newRequest("PUT", "/v1/agent/service/deregister/"+serviceID)
  	_, resp, err := requireOK(a.c.doRequest(r))
  	if err != nil {
  		return err
  	}
  	resp.Body.Close()
  	return nil
  }
docs: // ServiceDeregister is used to deregister a service with
  // the local agent