code: func (l *State) CheckState(id types.CheckID) *CheckState {
  	l.RLock()
  	defer l.RUnlock()
  
  	c := l.checks[id]
  	if c == nil || c.Deleted {
  		return nil
  	}
  	return c.Clone()
  }
docs: // CheckState returns a shallow copy of the current health check state
  // record. The health check record and the deferred check still point to
  // the original values and must not be modified.