code: func (l *State) AddCheck(check *structs.HealthCheck, token string) error {
  	l.Lock()
  	defer l.Unlock()
  
  	return l.addCheckLocked(check, token)
  }
docs: // AddCheck is used to add a health check to the local state.
  // This entry is persistent and the agent will make a best effort to
  // ensure it is registered