code: func (r *Runtime) ValidateRuntimeHandler(handler string) (RuntimeHandler, error) {
  	if handler == "" {
  		return RuntimeHandler{}, fmt.Errorf("empty runtime handler")
  	}
  
  	runtimeHandler, ok := r.runtimes[handler]
  	if !ok {
  		return RuntimeHandler{}, fmt.Errorf("failed to find runtime handler %s from runtime list %v",
  			handler, r.runtimes)
  	}
  	if runtimeHandler.RuntimePath == "" {
  		return RuntimeHandler{}, fmt.Errorf("empty runtime path for runtime handler %s", handler)
  	}
  
  	return runtimeHandler, nil
  }
docs: // ValidateRuntimeHandler returns an error if the runtime handler string
  // provided does not match any valid use case.